X axis lateral shift of 2.5mm after the first filament change

I’m printing some hueforge book marks. All filament changes are manual
I insert pauses via the preview slider and manually change the filament
After the first filament change, the remaining layers (which may involve another two manual Pause / Unload / Load Filament changes) - all align

Ive read of this on the forum - but not sure how/why its occurring.

PS: I’ve never done manual filament changes until the last4 days - everything else has been single color prints