i have pretty new bug for you, perhaps..
After upgrading a client with 2 vms to a new physical server (from 2012 hyper-v to 2016 hyper-v) we run all the updates etc. in the guest os. Everything fine.
It seems that there terminalserver (2008 R2 + Outlook 2010) started to create a new outlook profile every morning.
We started to do some test, log off the user in the middle in the day and log in again.
The .ost file was still there.
We then started to check if the nightly reboot of the server was the cause and prevented the daily reboot for a week.
Still; a new outlook profile was created since the .ost was goona.
The only thing left; lets look at the .ost files at some kind of database, perhaps Veeam is hitting it somehow with the Application Aware processing?
We disabled the AAP for that particular VM, and..
Seek and you will find; the .ost was there and no new outlook profile was created!
We turned the AAP the next day, and whooops, the outlook profile gets created again!
We turn it off, and behold; the .ost is just and the profile is like it was the day before.