SOLVED
Turns out upgrading to Acid 11 fixed the whole thing! It required a purchase, but what the heck. It was time anyway.
I purchased a couple of nice plugins, the Audiothing Outer Space and the Softube Fix Flanger. Acid Music Studio 10 recognizes them, but they go into the "failed" folder and don't work. I've tried putting the plugins in the Steinberg (it defaults to that for some reason), VST2 and VST3 folders, and results are the same. Anyone had this issue, and is it possible to make them work? They plugins work with Audacity, so I know it isn't an issue with them fundamentally.
I have a brand new PC with windows 11.
Thanks in advance!