I use Mp3tag ver:3.00c. I tried Tag Sources - Discogs Release ID. Input Discogs ID. But cannot use Discogs Release ID. Error message "Error connecting to server :www.discogs.com > 400:Bad Request". Please help.
I can confirm this behaviour.
v300b brings error 404
v300c brings error 400
I've fixed this with Mp3tag v3.00d. Thanks for reporting!
I confirmed the modification in this version.