Thanks for the suggestions... I tried odd and even modulos at $18 but that still displayed the same as before.
I'm assuming that by "although I turn bitplane DMA on after setting bitplane pointers" you mean setting the screen type after the bitplanes like so:
Code:
CopList: Dc.W WINTL,$2C81,WINBR,$2CC1 ; Window Size
Dc.W OVER1,$0038,OVER2,$00D0 ; OverScan Values
Dc.W HWSCR,$0000,PRIOR,$0008 ; HW Scroll + Priority
Dc.W ODMOD,$0018,EVMOD,$0018 ; Odd+Even Modulos
Dc.W BPL1A,BASIC,BPL1B,$09FC ; Bitplane 1
Dc.W BPL2A,BASIC,BPL2B,$49FC ; Bitplane 2
Dc.W BPL3A,BASIC,BPL3B,$89FC ; Bitplane 3
Dc.W SCREN,LOWR3 ; Screen Type
That did alter the display but also seems to have affected the sprites used to show the scores at the top, see attached... it's showing random flashes of blue so I guess the screen is even further out of sync?