Hi Mike, Thank you for reporting this issue. As a temporary workaround, can you please enable Preferences -> Performances -> Legacy Compositing. Our engineering team is working on this issue and should have a fix for you in a Ps v21.0.x release.
This issue was resolved in 21.0.1, which came out on 11/11. If you haven't already, please update Photoshop and uncheck the box in preferences for Legacy Composting to resume using the new compositing engine. Let us know how it goes!