The issue here is caused by a bug in the antivirus which breaks core OS functionality, so this is not something we can fix from our side.
To give you an analogy, a car manufacturer cannot make the engine run well when there is water in gasoline... this kind of issue is something you have to take back to your favorite gas station's owner (and, depending on the answer, change the gas station you are using altogether). Do you agree?
That said, maximum possible compatibility with antivirus software was actually one of the core design paradigms for us, and a lot of architectural decisions were taken with that in mind. For example, we implemented the dedicated changed block tracking mechanism for Veeam Endpoint Backup from the scratch - instead of simply reusing one we already had for years in Veeam Backup & Replication. So from perspective of the code we own, we've really done everything we could to ensure the compatibility. As noted above, faulting component in this case is outside of our code (Microsoft VSS framework), with the real offender being a bug in AVG which prevents Microsoft VSS from functioning properly.