How sure are you that the print head does not go beyond 99 mm? It sounds a bit strange… The lens distortion does make it difficult to see, but I might see signs of warping, and then you’d have a quite standard problem: The print warps a bit, which lifts it slightly up at the corners, and that makes the nozzle connect and push the print sheet away. Had this once, here’s my solution:
In my cases the print sticks well enough to the sheet so that the nozzle passes over the critical places and everything stays where it is supposed to be (apart from warping of course…)
If it is really that your Z-Axis stays at 99 mm I’d suspect a slicer/GCode error - assuming that your homing goes OK and the Z-Axis goes up to the top during homing… does it? That somehow would exclude a mechanical problem IMHO.