Please note that AV is not the cause. Disabling DLP on the client resolved the conflict. The question of why SQL filestream data cannot be brought online when DLP is active is still an open question though?
Is the problem a result of overly restirctive polices or the DLP install itself?
Have you tried removing all DLP polices (but still have DLP active) from the computer and see if the problem persists?
What operating system are you running the DLP agent on that's causing the issue with the sql server?