Shift-click inconsistencies

In 17b7 I'm noticing a lot of Shift-click inconsistencies in Media, Edit, and Color.

I will have an item selected -- a clip in an Edit timeline or Color, or a clip in a row of the Media Pool -- and then shift-click on an adjacent item to extend the selection, and the selection will instead switch to the other item. If I keep the Shift down and then shift-click the original item, the two are now selected. This can happen four or five times in a row before finally working correctly.

I've also notices that in the Edit timeline if I select a series of clips and, say, the first one is very short, if I try to grab that clip to move all of the selected clips, only the very short clip moves and the other clips are all deselected.

I can't duplicate this in Studio 17b7 for Windows. Works correctly every time.
Maybe a failing Shift key on your keyboard?

It's possible. This is with a (nearly brand-new) bluetooth keyboard, though, so maybe there are bluetooth or other interference issues.

Ooooh, Bluetooth.

I would (do) use a cable.

I use Apple's extended bluetooth keyboard and Magic Trackpad (which really is magical), and I've really only had problems since 17b7. I'll have to try rebooting my Mac. (Basically, I never reboot it.) It might be that there's a Big Sur bug or something.