@Proschi78
Tried the above and the movement behaviour became consistently erratic. Not sure as to why. Reverted back to the below and seems to be have "settled" to a somewhat normal behaviour. Potentially might reset the mbh6c and expansion board back to square one. Potentially the firmware updates may have left some things stuck which shouldnt be the case but never know as all the boards were still on 3.2 beta firmware when started up this time round.
M561 G91 ; relative positioning G1 H2 Z5 F6000 ; lift Z relative to current position G1 H1 X-450 F5000 ; move quickly to X Y and U axis endstops and stop there (first pass) G1 H1 U0 F5000 G1 H1 Y-450 F5000 G1 H2 X5 F6000 ; go back a few mm G1 H2 U-5 F6000 G1 H2 Y5 F6000 G1 H1 X-450 F360 ; move slowly to X Y and U axis endstops once more (second pass) G1 H1 U0 F360 G1 H1 Y-450 F360 G1 F6000 X243 Y200 G30 G90 ; absolute positioning G29 S1 ; this loads the contents of /sys/heightmap.csv