Laser re-home/origin keeps changing

I’m trying to do a number of laser etches as a workflow, and even though I set the work origin to the same coordinates, the Z axis seems to drop by “a little bit” (from about 0.1mm to 0.8mm) each time I do a run. The X/Y axies also seem to move, but they seem to over around the same 0.5mm-ish area, which I can live with. The coordinates on the screen say the exact same same thing, but there is a visible drop relative to the bed and the work piece with each origin, which happens at the start of every job. This obviously causes big issues with the laser focus!
I shouldn’t have to do a refocus every time I do a new work piece (this is literally “take the old piece off, put the new one on” - the machine is not turned off. I’ve tried both rehoming and not, the same thing seems to happen). Many people have complained that the origin keeps resetting to the centre, which is also a workflow issue that needs fixing, but this is a definite issue of accuracy and repeatability. Any ideas on what could be happening appreciated.

I noticed with the current 1.14.2 firmware and the 10W laser that you only get ONE chance to home (or I’ve managed to miss it otherwise). After you home the first time on power up, load a file and do either manual or auto thickness setting, the screen that lets you pick zero doesn’t seem to allow any home again. So you can’t just ‘re-home’ between doing files unless you power cycle, right now, assuming that would take care of the Z drop you’re experiencing.

Wonder if the extra weight of the 10w is an issue…of course I’m even assuming you’re talking about the 10w in the first place!!!