Pain isn't it as getting that focus correct is a real bind
Best way round it is to buy a few hundred of the square double sided sticky foam pads, one in each corner and one in the middle will hold your wood down while the machine cuts. No need to worry about cutting across the pad as it will still be easy to remove afterwards. Most market stalls or Poundland do 250 20mm square pads for a pound so they are handy to have in for all those awkward hold downs we all have to deal with.
best wishes
Dave