My system was a clean install of OS and PT's.
I then put my known working MIDI dev and patch-names into their locations.
Library>Audio>MIDI Devices (Here I put both
.midnam and .
middev files)
Also
Although I believe this is redundant)
Library>Audio>MIDI Patch Names>M-Audio (.midnam file)
Launched Pro Tools, added a midi track, called up my sound module checked the Patch and there were the names.
(I had tried this prior to 12.1 on a different system without success)
My testing midi sound module is the M-Audio Sono 61(GM)
I did build the midinames files way back when PT's 9 maybe..Avid required us to do that work.
(A few years back for sure)