Shift in Y axis 50% through print?

[KagisoRabada]

Hi,
Using Cura 4.9.0 and A30T and tried my first two prints.
At 50% through printing the same .stl file ( but with differing settings in Cura) I'm getting about a 2mm shift in Y axis for the remainder of the print.
Photos are a top view with two end views.
I've no idea if this is a Cura problem or a problem with the A30T.
The .stl model does not have this shift, nor it it apparent in Preview or post Slice.
Tomorrow I'll try using either Repetier or Easy Printer but some input from here would be appreciated.