I have about five leaves on my Naples Night and four of them are stiff and perfectly fine. One almost seems to have a broken mid-rib except that it is only in one place. The section of leaf before and after the floppy/break seems to be normal.
I have no idea what is causing this as I am treating it just like all my other phals and 99.9% of the plant seems to be fine. It's just that one section of leaf
and my cultural conditions sound very similar to yours.
The only thing I am going to do is pour some H202 in the pot and just keep treating it like everybody else in my phal family. Cross my fingers and hope for the best for all of us...
