Severe Error on DiffBackup with Altaro Software

We use SQLBackupAndFTP for FullBackup once a day + Diff-Backups every 30 Minutes.
2 Times a day “Altaro” VM-Backup is performing and backing up the full SQL-VM (HyperV).

After Altaro was locking the MS-SQL-Server DB and copying it, the DIFF-Backup of SQLBackupAndFTP is doing only a Diff since the Altaro-Copy. But Altaro is NOT creating a .BAK File, but a .MDB File.
So it is not possible to perform a RESTORE with a Diff, because there is no correspoding .BAK.

This is a severe security problem as the last point of restore is the time of Altaro Backup.
So we lost the complete Data of 6 hours of working on the DB.

Why is the “copy” of the MDB of Altaro setting back the DIFF to 0 ?
Why is SQLBackupAndFTP not realizing that the last “full backup” was not performed by SQLBackupAndFTP ?

This is not to blame SQLBackupAndFTP but at least a restore with SQLBackupAndFTP is not possible even if everything worked fine with no errors.

Attached a hardcopy which shows the broken Diff-Sequence.

Hi Michael_Hinterauer,

When you use two backup tools your backup chain breaks. Please find more details about it at https://sqlbak.com/academy/backup-chain

Also, you can find more details on how to resolve it via SQLBackupAndFTP at Solved: [JOB-BAK:2006#11008] Previous Full backup of a database was created with a different application | SQLBackupAndFTP's blog