Given a profile named "Hawai`i", clicking on the yellow warning triangle in the "Log" column gives this popup:
Cannot open file "/Users/me/Library/Application Support/FreeFileSync/Logs/Hawai`i 2025-05-30 141619.413 [Warning].html".
Exit code 2: /bin/sh: -c: line 0: unexpected EOF while looking for matching ``'
/bin/sh: -c: line 1: syntax error: unexpected end of file [open "%x"]
The logfile does exist and can be opened by navigating to it in the Finder and double-clicking.