You are using a Tina 4.6.9 or 4.7.1 CR version to backup a Hyper-V environment.
A problem has been identified when browsing the restore interface of a Hyper-V application potentially triggering the removal of backup versions in the catalog.
We strongly advise you to upgrade your Tina version to Tina 4.7.1-P6432 or later to fix the issue.