@HaDeZs what is your z-axis hardware? I was having a similar problem with the Z-Plus. It turned out there was play in the anti-backlash nuts.
The problem:
The fix:
I think what was happening is everything would zero out fine to the material surface, but the thrust of the router motor actually pushed the z-axis down more taking up the slack in the anti-backlash nuts. It was not much, but exactly what you’re reporting - about a 16th" too deep on the first pass.
You could see similar with other hardware, like bad v-wheels, loose motor pulley, stretched z-axis belt (on the original belt-drive z-axis), or worn bearings in the router. Here’s how to replace the bearings in the Dewalt:
Based on what you’re reporting, I’d suspect a hardware problem foremost, unlikely software will be the issue.
(One last one I’ll add - I’ve noticed some spoil board deviation with temp and humidity changes causing the middle to raise just a bit. That means when zeroing on the front left, cuts that are happening towards the middle will be a bit deeper. Not sure if it is the fiberboard swelling with humidity or the steel slightly changing shape with temp… project for another day )
)