Cuttings were doing great. New leaves, filling with fat, white, healthy looking roots. My first cuttings to go to a cup was looking great, then over the course of 2 days the leaves dropped, roots turned brown and I lost it. Now my next cutting seems to be going the same path (see pics). All the other cuttings in the same humidity bin are fine, but I'd like to keep them that way. Condensation on the inside of the cup so I don't believe they need water. Plenty of humidity in the bin. No over watering, only dampened the soil/perlite at the time of cupping and gave 2 tablespoons thru a syringe 3 weeks later. Any ideas?

Last year, my first year doing this, I had much better results and I feel like I did more or less the same thing.

Only differences:

Last year gave the cups a good watering when cupping, this year I moistened the soil in advance.

Last year I had the cups inside a darker cup to give the roots darkness, this year I used larger cups so I couldn't find larger dark colored cups to match.

Last year I had a gnat issue so this year I baked the dirt first.  Not a single gnat thus far.

Yellowing leaves in the background, might need fertilizer?

Are you talking about two cuttings of the same variety only that are doing bad?

If the cup was in the window, it might have overheated in the sun.
Always a good idea to keep the roots in the dark, even if all you do is wrap some newspaper around the cup to keep the root area out of direct sun.

If it were mine.....I've give it some Dyna-Gro.....3 teaspoons per gallon.  In my opinion, sometimes there just isn't enough stuff in steril soilless mixes to keep a "tired" cutting motivated to keep growing.  I like Dyna-Gro. 

Chome360,
The roots and mix at the bottom of the cups looks dry. Are you using bottom heat?
Soil contains microbes and some may have survived the baking if the temperatures didn't get above 180 deg F. The soil microbes can cause rot on the end of the cuttings if they are not callused.
The new roots also need to be protected from light.

or, the roots are all at the bottom and not getting any water. if the cup is still light, let it sit on very weak fertilizer for 5 min and drain

Lots of possibilities here, hard to tell without being able to look closer and knowing more.

With a large cup and pre-moistened soil, the outer soil won't be drying out and might be wicking to the center and keeping it too wet.  That's one reason to not move into too large of a pot from one step to the next.

Also seems that all the roots are on the bottom and as mentioned above by Pete and re-Pete, the soil looks like it can be dry there.  Try bottom watering.

Condensation is only a sign that the inside of the cup is warmer than the outside. As water turns to vapor and moves out of the mix it hits the colder sides (or when on a heat mat, the top) and condenses back into a liquid. So it only tells you there is a differential really, if the temp were equal there would be no condensation even if the mix was soaked.

ascpete, sterilization can cause more problems in some circumstances because it creates a biological vacuum. When treating soil it is best to pasteurize it at a temperature between 140-160 f so that heat resistant bacteria survive and quickly repopulate the mix, Bacillus subtilis is a good example. Fungi and bacteria spores are reintroduced from the air as soon as the soil cools and food is not more easily available to them because the heat causes starches to turn to sugars and any fungi mycelium that was killed during the process will also now be consumed without putting up a fight.

I think its the soil, probably over fertilized

Thanks for all the insight guys. To answer your questions...no bottom heat. The cuttings are not in the sun but they are under grow lights. The cuttings don't feel overly light. Both cuttings are from different sources and varieties. I do keep a pool of water at the bottom to keep the humidity up. Some roots even grow out of the cup and dip into it. Solid is the same that I used last year without issue.

One idea I had was that algi could be growing from the exposure of the roots to the grow light. The first cuttings I tossed did have some green fuzz growing out of all the holes.

Algae is wet and slimy. Molds are fuzzy but green molds are not supposed to be harmful to plants, they do attack other fungi so it is possible that something else killed the cuttings then the green mold killed it. 

I always do an autopsy, then you will be able to get an idea of what went wrong. 90% of the time the bark near the base is rotting, IME.

bark rotting indicates water problem. something is causing water from draining freely... but if it's not over watered, roots look healthy, top has moisture, and no gnat... what can it be? i know no gnat doesn't mean anything. but gnat is attracted to wet rotting matters. if the cup in not too light, there should be water so it's not underwatered...

Rotting bark without fuzz is bacteria, which love wet conditions. Rotting bark with fuzz is fungi of some type, which love stale and humid conditions.

In the case of the pictured cutting it might just be that the roots have used all the water that is available to them, since they are only at the bottom of the cup. My guess is still a microorganism though. If they are not on a heat mat and have that much condensation it is probably a sign of thermogenesis from a large population of fungi/bacteria.

You are not alone. Same thing is happening to me.

I have found that bark is not a good ingredient to introduce to indoor plants at all. It has a very high rate of molding, whether sterilized or not. I haven't seen a problem with it outdoors but that may be because I live in an arid environment.

Here's a little experiment that might help: Place your preferred soil in the container and the location that you intend to put your cuttings and see how the soil behaves without a cutting in it. I did this recently with my incubator and small pots in order to calibrate the incubator for pepper germination. To my surprise the pots started to show mold and it was the bark in it that molded. I bought the potting soil at Costco; MG Moisture Control Potting Mix. I ditched it and got ProMix HP, as has been suggested here, and have not had mold issues with it.

I meant the bark near the base on the cutting, sorry for not being more clear. 

When cuttings collapse suddenly, for me, usually a pathogen has entered through the base and is moving up the cutting. While the roots may still look OK they have been cut off from supplying the top of the plant. The bark changes color, shrivels, and slips from the cutting. Above that the bark looks normal but the cambium is brown as the microscopic fungi filaments or bacteria invade the vascular system. It can happen from the top too if conditions are humid enough. 

Hi chome360,
I would up pot. I would never allow a small tree to get her roots air/light pruned.
I would use regular compost as the small tree needs food to grow .
I would water from the bottom .
Are those trees near a window ? If so move them with the lighting system to a dark corner of the room.

I have 2 cuttings ( suckers that I pulled out the dirt with no roots ) - and since last week I've been watering from the bottom twice a week - Until now /since December 2013 /once a week was more than enough.
I changed the lighting system a week ago and the new 2 T5 bulbs are heating more - and as we moved to some more spring weather, the heat has been higher around those cuttings.

I would guess moisture issues, probably too much overall.  The roots don't look all that bad.  Leaves on top could shrivel just from moving from humid location to dry location.  Or it could be impending death.  Hard to say for sure.  As long as there are some whitish roots there is a chance of survival.  Maybe lay off watering for awhile.  Or only mist the top a bit to keep soil from drying out completely.