Dude I have the same problem. It doesn't seem to affect anything in the composition though thankfully.
Edit : I think it may be screen tearing my composition :/
Actually,I can still import Premiere Pro sequence with this problem. It seems like doing nothing here.
But I've already fix this. You just uninstall After Effects, then reinstall it. Sometimes uninstalling and reinstalling can fix many things.
Reinstalling didn't work, and I'm still getting tearing previews in after effects :/
Your issue is likely to be unrelated. Please start a new thread and give us a lot more information (screenshots would be really helpful too).
I've reported it as a bug already.
1 person found this helpful
Reporting it as a bug is good! It lets the After Effects team know you have a problem and, if it's a bug, they can fix it in an update in the future sometime.
However, it does not do anything to get you help now if there's a way to fix it now.
3 people found this helpful
Delete "PremiereProImport" plugin file from C:\Program Files\Adobe\Adobe After Effects CC 2017\Support Files\Plug-ins\Format\PremiereProImport folder.