I have a problem where small rafts don’t stick at the center of the build plate but stick fine along all 4 sides. Anyone seen this issues before?
Roughen the build plate with some heavier grit scotchbrite and wipe the plate thoroughly with IPA to remove the particles of aluminum, this helps a lot
If what Paul suggests does not help, it could also be that your resin tray has some cured resin near the centre, so the laser can’t hit the build plate in the centre with as much intensity.
Usually when this is a problem the first symptom you see is undercured resin and delayering.