'Thick line' issue with Anycubic Mega 2.0

[swam]

Everything seems nice and tight, nothing in the way of the X gantry etc. It MUST be a batch issue.

Interestingly, the listing on Amazon which was in-stock has currently gone out of stock. I wonder if they had a few returned with the same issue?.

[curious aardvark]

try this.

print a block 11mm high say 20mm on a side.

LEAVE it on the bed.
Then print something else 20mm high on top of the existing block. ie starting at 11mm
And see if you get the problem at 11mm on the second print.

If you do - then somehow it's in the software/firmware. if the second print is fine - then it has to be a mechanical error.

Well you can't do it in prusaslicer, annoying. it's a piece of piss in simplify3d.

see if cura will let you do it.

It needs to be two totally seperate print jobs, not two things stacked in the same print job.
We need the software to think it's starting a new print.