Weird new editing anomoly in PT 2021.6

[innerbooty]

Hello,
Just in the last few days started getting a weird thing while editing in 2021.6 (Mac Pro Cheesegrater flashed to 5,1, Mojave, RX 560 4GB) Been working great for a year and a half, and I've never seen this before. I will be happily editing away then do some kind of edit, move a clip or something. And then suddenly when I go to highlight any region or clip in the edit window I don't get the shaded edit region anymore. I see the blue guides on the timeline indicating the start and end of the selection, but the selection itself is no longer highlighted in the edit window itself. Really annoying. I have to fully quit Pro Tools and re-load in order to get the highlight back. Any thoughts...?
Thanks!!