The current version is 3.3 though we didn't post the link for older displays because the other changes were for LED displays. It's worth trying this version in case the fix wasn't picked up properly in 3.1.
https://www.colordmd.com/download.php?rom=HS2_3_3
Save the file to a flash drive with the exact name COLORDMD.ROM. Make sure there are no added characters in the filename (ex. COLORDMD(1).ROM) or it won't be recognized by the ColorDMD controller board.