We get log backups from the secondary node. But now I see that log_since_last_log_backup_mb in sys.dm_db_log_stats returns null for databases which are in Availability groups, so Ola Hallengren's log backup procedure with
@LogSizeSinceLastLogBackup = 25,@TimeSinceLastLogBackup = 21000
limitations works on those databases. The backup process is currently working on the secondary node.
But I could not understand why it returns null? Have you encountered such a situation?
The following pictures show result of log size since last log backup on the primary and secondary nodes.