Hello again,
So I actually am having similar issues again and not even the changing the Gamma Correction to Approximate is working. I think however, I may have just isolated the issue a bit further. Again, not sure why this is, but here it is. The issue mostly appears when I am trying to edit with the sequence setting put on the H.264 compression (In Sequence Settings), when I change it to a different compression (I usually use Apple ProRes22 HQ), the issue takes care of itself. Well, I hope this has been helpful (if anyone finds out why this thing is happening in the first place, please let me know!). May your project get finished before the your computer is thrust through the nearest open window.
Grayson M.