I remembered something I did that may be part of the problem, for I'm getting odd behavior out of the whole system now.
My Superior Drummer launches, but won't load the sound files either. Remapping right to the sounds gets recognized by the plug, but then nothing happens.
I swapped two of the smaller data drives (No programs on the drives, only data for programs) recently for two 500G drives via a straight copy. I set up the system the same afterwards and figured "done".
Everything looked fine following, but now I wonder.