Using Affinity Photo 2 on macOS Ventura 13.1
It happens almost all the time; even with new files
No add-ons except backup drive; even does it with drive disconnected
1. Selection tool scale is off; trying to select a pixel size from 1 to about 170 with precision is almost impossible
2. The selection circle doesn't always respond to the pixel size selected in top menu bar. When a low number of pixels is selected in the tool menu the circle will stay at the previous size