One WAV file is still "wrong size", but down to 1 from over 100 is a marked improvement. Thanks for the heads-up on that.

Regarding the CMP file in the settings folder, the only thing I could find out of whack was:

Misc_MissingBIOSRoms = 2

But the problem I'm having is, it's not telling me which ones are missing. The Scan Results window comes up empty. For grins I clicked the Set Information button and the Set Information window appeared for ALL the sets.

I understand that something changed from MAME 116u4 as far as the way BIOS roms are handled, but the technical stuff is over my head. I feel like I missed a step somewhere...