Back of bed being ignored?

[Laksha1]

I've been battling a problem with my print space. In Cura 4.0, the print fits fine (a 310mm circle). As well it should, it's 10mm under the full size right? Well it does fine all around except the back of the plate. At least a half inch is being ignored. The circle will "flatten" when it gets to that point like it's being limited. Anyone know what causes this? I'm using the cura profile someone posted here recently for 4.0 also.

And I'm now noticing, the right side of the bed is doing it too, although not quite as badly.