I planted a small fittonia albivenis in a bioactive vivarium about a month ago (and have only just introduced my gecko to the tank last night, so he can be ruled out as the cause of the problem). Since I planted it, the leaves seem to consistently wilt and drop off, though the plant itself doesn't seem to be dying--the stems are still firm and green, and it continues to grow new leaves, many of which are still dropping off. I thought maybe it was shock, but it's been weeks--and I don't know enough about plants to know whether that's normal or not. The temperature in the vivarium is 70-75 degrees fahrenheit, the humidity averages around 60% (spikes up to 80-90% and dries down to 50%, but usually hovers around 60% the longest), and the soil is kept moist but drains well. I have two 13w Arcadia Jungle Dawn LED grow lights above the tank. I also have a fittonia verschaffeltii planted in there as well, under the same conditions, and it's thriving, which is why I just can't figure this one out. I do mist the tank, usually twice daily, and I wondered if maybe it doesn't like its leaves being wet--but again, this doesn't seem to bother the other fittonia. I've been trying to avoid misting it directly, at any rate, just in case. The only other thing I can think of worth mentioning is that it is partially shaded by the pilea nearby.
I found a couple other threads regarding fittonias, but the issue with those seemed to be more with a lack of humidity and the leaves yellowing before dropping, which mine aren't doing. Can anyone tell me what might be the problem, or what I can do to help it?
Hopefully these pictures are helpful, and I've included a picture of the other fittonia for comparison:
edited to add this photo of the bottom of the viv to give an idea of its surrounding conditions (bottom right, in between the pileas):