Filament doesn't retract for some travel movements using PrusaSlicer
Minimum Travel after Retraction is exactly what it says on the tin: if the travel after a retraction would be less than 2 mm, it does not retract. You'll want that to be short, but not 0, because retraction can lead to under extrusion at the start of a new line, and every swap from one shell to the next shell right next to it is classed as travel.