Electric Blue Johanni missing part of it's tail

One of my Electric Blues has lost part of her tail. There is no sign of
infection but she is keeping pretty much hidden. She also had an assignation
with one of the males in a cave this afternoon, quite fascinating to watch.

Should I just leave her be and monitor her progress or should I be more
proactive and possibly move her although I'm not sure where to (my QT tank
is currently housing a Betta).

Water tests out at 0 ammonia and nitrites, around 10 nitrates and pH of 7.5

Any thoughts would be appreciated?

Thanks
Gill