Ah, that's new. I don't have a manager so in my experience they're just ignored.
Viewing post in OPUS support?
Figured it out. The calculated sample rate of the OPUS files I'm testing with is ZERO. There's some math in my plugin that divides by the sample rate at one point, and division by zero = bad result.
If there's some equivalent of the sample rate in the metadata, or if I could fake it somehow, this could be patched.
All this said: The variable mix stuff - the meatiest part of the plugin, and the whole reason I made the plugin in the first place - still work as intended. I haven't yet tested every feature, but the loops seem like the biggest thing likely to break that did, in fact, break.
EDIT: Nope, one more thing is broken: the "Play from" (or "Starting point") attribute hangs the game.