This time around, the music-only exFAT formatted SSD that I couldn't get to mount on Snakeoil was not formatted by me. Moreover, it is the same one that I used without issue in the same sever when it was running Volumio.
My solution was simply to replace it with an EXT4 SSD that I had on hand...so I'm not urgently seeking a fix. Just mentioning it in case I can assist you in diagnosing the problem by putting the exFAT SSD back in and running any ssh commands you suggest.
Cheers,
JD