I am cutting with the lasersaur at 100% and the cut starts good but half way trough the laser just stops cutting. You can see the cut starting to fade away.
Looks like an optics alignment issue. Odds are the Laser is still firing. Where does it stop cutting? While looking at the machine, is it from left to right or front to back. Something could also be blocking the beam when it moves to that position.
It is from left to right
Probably alignment but also check the temp on the chiller. The CO2 tubes can lose power as they heat up too much.