She gets scared and pulls out of the jump. This has been going on since January. She has completed the jump before but fell very hard causing her to be more afraid of the jump. It is not unusual to hear of a skater who easily landed all their single jumps and then have the problems you're describing on the axel. Although 6 months may sound like a long time to learn a jump, especially when the other jumps came quickly, for the axel this can be within the expected time frame.
Many skaters contribute to the problem by losing their confidence.
If your daughter has fallen hard, she may be holding back. If she does not wear crash pads, or other extra padding, you may want to invest in some. This can be expensive but they do help considerably. Discussing the issues may help and if she is aware that this happens to other skaters may help her self-esteem. The other part is try to not put any extra pressure on her to land the axel.