Also my plant seems to be rotting and decaying along the edges of the leaves in the "cup" area. I've read this can be a result of keeping water in the cup, but I am confused because it seems one camp of people advising keeping water in the cup and another says it is not a good idea.

Would it be worth trying an alternative for awhile, like misting once a week rather than keeping water in the cup? Or is there some other way I might treat this problem?

Any suggestions would be appreciated.

Although I'm not an expert in these matters, I have a couple of suggestions for you to consider.

Is it standing in a saucer where it always has contact with water? If this is the case then it probably has 'wet feet' which will possibley lead to rot.

Has it possibly been exposed to CCA treated wood? i.e. drips from overhead CCA treated timber beams, leaves touching a CCA treated wood product or perhaps a mulch of wood shavings or chips from CCA treated wood.

Is it or has it been in contact with any other copper products (copper is very bad for broms)

Have you sprayed it with a fungicide containing copper? If so it will have a similar effect, unless the copper component of the spray is very low.

Has it been over fertilized? Sometimes this can manifest itself with leaf dieback.

I can't think of anything else at the moment but these are all things to consider, but it would be easier for the experts on this site to help if you posted a picture of the plant in question.

All the best, Nev.