Not sure what, but When I plant stuff, 3/4 of the time it's not growing. There was one fairly remote cave which I nearly filled with seeds, and only two of them showed up, and one poofed on a reset.

I've planted serveral more since then. None of them have showed up. Neither are ones I have planted in other areas since.

What's going on, why are the fruits of my labor not showing up?

Because the system isn't working as intended. This is, like, the third time this question is answered. >.>

Also. Despite the fact I am being told, there are in fact other types of plants IG, neither I nor a few other underdark scouts can find anything other than bluecaps [that is harvestable].

I can provide a list of all the areas and routes I have looked along (quite thoroughly) and I could not find a single one. I have been told of other ones being seen awhile back IC by other PC's, I go to those places and there is in fact nothing there.

So is the 'not working as intended' somehow responisble for this?

Possibly.