1) Flashback logs in flash recovery area aren't purged.
2) Reclaimable space of flashback log is not reflected in v$recovery_file_dest.
(i.e inconsistency between reclaimable space in v$flash_recovery_area_usage and v$recovery_file_dest).
3) Archivelogs disk backups aren't prefered over tape backups for RECOVER, BLOCK RECOVER and FLASHBACK command.
4) Archivedlogs needed by Guaranteed restore point are deleted by BACKUP ARCHVIELOG ... DELETE INPUT command.
Cause
This is due to BUG:5106952 FLASHBACK LOG SPACE NOT BEING RECLAIMED