When printing full Bed, x Axis Perimeter incorrectly offset  

When printing full Bed, x Axis Perimeter incorrectly offset

This is an interesting one for people, however, I can't seem to figure it out and happy for feedback.

I set a print up for printing out 8 x 6 washes... using up the full bed.

In Slicer PE, latest edition, It looked fine and filled the entire 250 x 210 bed size.

When it went to print, it offset the "perimeter" approx 5mm to the right.

Now the interesting part is that although the perimeter was offset to the right, the washes were concatenated on the left side (i.e. part of them was cut off but they seemed to be correctly located on the board per the Slicer view.

The right edge of the perimeter printed on the very edge of the right hand side of the print bed. The left hand side was approx 10-15mm in from the left hand side.

I cannot see any settings in the Slicer for correction and the printer seems to centre correctly on all other prints...

Any thoughts welcome.