Configuring managed backups schedule at 5 minutes intervals for transaction log backup is not honored. The feature backup the log at 10 minutes intervals instead of 5.
I've attached a screenshot with an example.
"managedbackup.fnbackupdbconfig" shows it is configured at 5 minutes intervals but when querying msdb for backup history, the log are being taken at 10 minutes intervals.
I've also restored one of the affected database to make sure that the log chain was not somehow broken and confirms that nothing else occurred between two log backups.
No error in the SQL Agent logs.
No error in the SQL management logs.
I've also tried the 00:00 configuration but like the documentation states it stops taking log backup which it did. Re-configuring the 5 minutes intervals afterward didn't help in any way.
This behavior occurs on SQL Server 2017 CU22 and on SQL Server 2016 SP2+ as well (they are stand alone instances per VM).
Databases use the proper compatibility level (140 or 130 depending on which instance is tested)
Recovery model: Full (of course) and it didn't change during any of the tests.
Database size is not a factor because it happens to extremely small one (less than 100 megs) up to some heavier ones with more than 100 gigs.