Synthetic Full Backup Failing Due to Veeam Immutability?

[wa15]

I have a new Linux hardened repo deployed with Veeam immutability enabled (30 days).

I have weekly synthetic full scheduled, and backup mode is incremental. I also have weekly GFS (12 weeks) and Monthly GFS (12 months) enabled.

The first weekly synthetic full is failing with the message "Unable to perform the operation: a backup file is immutable".

Any ideas?

[Gostev]

I doubt it is actual synthetic full operation that is failing because it could not care less about immutability enabled on source backup files: it does need to modify or delete them, only read. Most likely, some other operation is failing.