[Killer-Velo Custom]

Changed an engine in the above vehicle due to aqua locked engine. Used same spec engine from same MY vehicle. Bolted original zf8 gearbox to it & reinstalled to vehicle. Engine starts & runs fine, but gearbox will not shift out of park. Vehicle recognises gears are trying to be selected, as it asks for brake pedal or select button on shifter to be depressed, but it will not shift from park. The lever on the side of the gearbox is closed so transmission is live. There are no warning lights on & having had fault codes read, nothing shows up? Any thoughts or manual work rounds to be had?