I have been dealing with this problem for a long time but it is caused randomly.
I have a backup server running Windows Storage Server 2016 with Veeam Backup and Replication installed on it. I have three backup jobs on it. Those jobs are:
1. Backing up a Hyper-V server
2. and 3. Backing up two different virtual machines hosted by the Hyper-V host backed up in the job numer 1.
Well these jobs never overlap each other and they are run each daily. The last job run each day it's the job number 1 (Hyper-V host) because it takes the longest to complete.
The issue here is that sometimes the last backup job gets stuck for some reason and in the next morning it's still backing up, so all the resources in the Hyper-V and its virtual machines are unavailable. If I access the Hyper-V host, I can see all the virtual machines state as "Making a backup copy". I don't really understand this message because all the virtual machines are already backed up, but the host backup job is still running.
As this is a production enviroment and I'm dealing with fire, I tried to fix this by making a denied window in order to stop the backup job of the Hyper-V host if it exceedes the expected the backup time. But this morning I observed that even this being well configured, it keeps "stopping backup" message but it never stops, so I had to manually shutdown the Hyper-V host so the resources would be available again.
The backup window configuration is as it follows:

Despite having many questions about this, the main one would be: why does it take so long to stop the backup? I have observed that at 7 a.m. the backup job was still "stopping" even though being all night "Denied" by the window that I have configured.
Statistic report:

Thank you so much,
Isusko