There are several systemic fungal diseases that result in yellowing leaves. & aphids etc attack weakened plants. IF the newest growth is also yellow then destroy the cuttings.The parent plants MAY be saved by heavely fertilizing & HOPE the new growth out races the infection.the rapidly growing tip is then propagated. OR purchase new disease free plants...

I usual do my cuttings in my basement that stays between 50 and 60 degrees so your plants may be getting too warm and pouting about it.

Yellowing leaves may or may not be a problem. I would take a "wait and see" approach before doing anything drastic. Major leave loss or stem rotting will tell you if you have a disease problem. Some yellowing or leave loss might end up being an environmental problem.

Fertilizing a sick plant is NEVER a good idea and of course, you do need to take care of the white fly problem.

I also find with geranium cuttings that the more I ignore them, the better they do. My method is to stick a stem in some medium and watering occasionally when it starts getting dry gets me more plants than covering and fussing over them.

Hi Laurie - not sure if you are still monitoring this question, but I think that the yellowing leaves are low light from coming 'indoors'. I got a couple of tips for starting them, and I haven't lost too many since:
Take cuttings after the little frills at the joints brown. Leave them dry for 24 hours, then pot up. This seems to work very well. Hope you didn't lose them all - I now have WAY too many cuttings. 8-)

Has anyone ever started cuttings without leaves?