Well, it suddenly stopped compressing once again so I went ahead and removed fiddb and after indexing 7,220 files it cranked right up compressing once again.

OK, that's good news, that just means your database got a bit confused (rather than there being any more serious bug). We probably ought to put a menu item in (under Troubleshooting, or some such) to rebuild the database, rather than people having to faff about on console...

Peter