Using Krita 3.3 and 3.3.1 (64-bit, portable edition) on Windows 10, with DirectX because of **** Intel graphics... I use a Wacom Bamboo tablet.
3.3 improved performance a lot, but on my low-end, old computer, I often have drawing lagging: I often does hatching, and sometime the drawing suspends a second or two. I wait, and see the lines to appear... But that's not my bug.
Since 3.3, when I switch from brush to selection (square, polygonal, free...), I often cannot trace a selection on first use, I have to repeat the selection to see the marching ants...
Of course, as I try to reproduce this, it works properly, except once...
Oh, I see: out of habit, I tend to use the mouse to do selections... So when I switch from the tablet pen to the mouse from brush to selection, the first click / drag is ignored.
I am pretty sure I hadn't the problem in previous versions.
Now, it might be a too minor bug to bother to fix it specifically.