Actually, it's somewhat baffling that it happens even when scene buffering time is 1500. Okay, it appears to be a weird timing thing that I never really see. I have an idea, but I cannot guarantee it'll work, it's just a total shot in the dark here and I sometimes use this to try to fix timing issues for people, but try this:
1.) Open a command prompt (run the command prompt as admin)
2.) Type: bcdedit /set useplatformclock true
3.) Restart windows, try OBS again to see if it affects anything
Again, it's just something to try, but I feel like it may not work. If it doesn't, I may run some more tests on you some time, if you happen to have time later.