This issue concerns users that use HVDS as a backup media typically with HVA
Under certain circumstances the catalog maintenance task will purge hvds backups (streams) that should not be deleted
Tina 2020 (4.6SP7)
A patch P6272 has been build and is available on support.atempo.com
In the meantime to avoid the issue you should add the tunable below to the catalog server.
Please remove the tunable once you installed the patch.