Hello Dino,
Please check SOLMAN_BTC user roles in SOLMAN_SETUP---->system preparation,
Check any user related with SLD and LMDB sync has been marked for Authorization updation.
Please confirm any of the the landscape systems got upgraded recently. If yes...you might have to check supported CIM content.
in RFC destination LMDB_SyncDest1...change user name and password and try again.
Regards
Anand