I just noticed that a ZIP file with a FILE_ID.DIZ in it hadn't used the DIZ for the description, which I though was a bit odd.
Upon strace inspection, it appears that Mystic is looking for file_id.diz but not FILE_ID.DIZ when importing (e.g. when choosing (E)dit --> (I)mport DIZ from a file listing). Perhaps it should check for both?
Best regards
--- Mystic BBS v1.12 A47 2021/08/05 (Linux/64)
* Origin: Star Collision BBS, Uppsala, Sweden (2:201/137)