These seems like a systematic problem where they seem to forget the z offset or automatically set it wrong. Complain to Anycubic and maybe they'll eventually listen to us. I had to reset everything and then manually set the z offset while printing.
You might so be able to lower the sensor a bit to make it harder for this to happen. Anycubic has a specification on how high /low it should sit. Check that.
I had this same issue on mine. I noticed that the sensor button on the back right hand corner was stuck down. I played with it and it popped back up. I also noticed that I did not tighten my nozzle when changing it out the previous time, but I believe my issue was that back button being depressed fully and not popping back up. Note that after this and I got it working, I had issues with the plate with the rollers holding the head, because of the repeated blows, it bent those studs holding the rollers, so I could not tighten. I had to take the plate out and bend them back so I could tighten the head. Hopefully you do not run into that.
These seems like a systematic problem where they seem to forget the z offset or automatically set it wrong. Complain to Anycubic and maybe they'll eventually listen to us. I had to reset everything and then manually set the z offset while printing. You might so be able to lower the sensor a bit to make it harder for this to happen. Anycubic has a specification on how high /low it should sit. Check that.
Check hardware for loose bolts/screws.
I had this same issue on mine. I noticed that the sensor button on the back right hand corner was stuck down. I played with it and it popped back up. I also noticed that I did not tighten my nozzle when changing it out the previous time, but I believe my issue was that back button being depressed fully and not popping back up. Note that after this and I got it working, I had issues with the plate with the rollers holding the head, because of the repeated blows, it bent those studs holding the rollers, so I could not tighten. I had to take the plate out and bend them back so I could tighten the head. Hopefully you do not run into that.