I have no idea if its the camera or something else...I can tell you that I run many dahua and hikvision cameras with blue iris and dont have this issue.
Have you excluded blue iris system and storage folders from virus scans?
No virus scans. I'm almost willing to chalk this up as some incompatibility between the uvc-g3 and blue iris. Ubiquiti doesn't seem to follow industry standards with these cameras. They probably just hacked rtsp support in there as an after thought to appease customer complaints. Googling and searching the unifi forums doesn't turn up much results for people running blue iris with these cameras.