Warp Stabilizer playback bug
I have narrowed this issue down to using the Warp Stabilizer effect. When it's enabled, the frame shifts during playback or playhead scrolling (see attachment) but does not shift while the playhead is stationary. It doesn't appear to affect the renders which is good. When I disable Warp Stabilizer the frame shift is gone.
Kristyn Antone commented
this isn't a fix, but a workaround for this. Add ".1" to the scale of the clip and it will play correctly. So if the footage is scaled to 100%, put "100.1" and it will play correctly.