4.3: odd failures to load VSTs for playback in existing project

Poking around at other issue reports on the forum, this summary looks like the same behavior I’m seeing (though the original report was of different issues):

I’m deeply sympathetic to the follow-on note there:

I’m very much at a loss at the moment, though—I suppose maybe I can try to recreate the project from scratch, adding in each of the flows, and copying and pasting over the materials?