Edit Block; dragging days of week goes screwy after first move?

Just curious whether anybody else has seen this; not sure why I’m not pinging support, but…

After changing my plant to mid-volume masters, the calendar defaulted to TueWedThuSatSun, a day later than I’d like, and while I’ve only got a few weeks left and moving things as I do them isn’t a big deal, I was going to save myself the trouble and just set the default days for the rest of the block.

When I click the block name, I get the Edit Block panel on the right (which is a bit fiddly for this kind of thing with the days all stacked, but okay). I can drag the Tue block to Mon, but then when I try to grab Wed to move it to Tue, it seems to vanish, and if I move the mouse further it looks like I’ve got Sat moving with my mouse, but several inches separated on the screen.

Am I doing something wacky to even cause myself to be trying to drag the week around in that squished panel?