Possibly dehydration? Only a guess, because I'm new to growing these, but when I recently received a couple of cuttings, I learned that a regular misting of the plant could help in raising the humidity level. I've also been following this thread in the Plumeria forum...
The thread "My 3rd attempt" in
Plumeria forum
It's been helpful for me as I'm learning more about them.
Maybe
@Dutchlady1 could also chime in?
