Optical Flow Broken by Lumetri Color
When a clip is slowed down with Optical Flow, it works just fine. However, when I edit the clip's color using Lumetri color, the Optical flow functionality disappears and the clip becomes choppy.
The only fix I have found is to Render In to Out, then change the color, then Render In to Out again. It's a frustrating process.

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Markus Wernig commented
I've been extremely frustrated by the exact same bug.
I edit Hollywood movie trailers for a living. I use Optical Flow a lot in every sequence to fine tune the timing of shots. At same time I rely on Lumetri Color to make things look great.
The fact that Lumetri Color breaks Optical Flow for playback is not only very annoying, it's also slowing me down - and I am constantly up against very tight deadlines and fast turn-around times.
Please, Adobe! It's nice that we get new Premiere Pro features once a year, but if you could fix bugs like this one first - that would be applauded by everyone in my industry.
Thank you.