Almost all of the time when reopening a project, the magic mask data is corrupted/invalidated while still showing that it's cached. The only way to fix it is to delete and retrack all clips which takes really long if it's used a lot. Sometimes the regenerate all clips feature doesn't actually redo all nodes on all clips in the timeline.
I already had this issue in 20beta2 and it's still present in current 20beta4.
Here is what the data looks like when in highlight mode(minus the black censor squares). (scroll down in the image to see the track being blue)

- 2025-05-27 15_46_31-DaVinci.png (379.2 KiB) Viewed 169 times