CAN'T GET GPS FOR SPEED TO WORK

Hey guys,

So I’ve managed to get my tablet connected to the Link G4+ ECU and works good but because my car (92 Skyline) uses speedo cable for SPEEDOMETER - I have to use GPS on the tablet for my speed. I’ve chosen this as an option but the app is still detecting 0 KM/H.
Anyone else run into this issue or knows of a solution please?
TIA

units and values ​​2 i page.
if set to “vehicle speed is not GPS” -delete and set -GPS

so I’ve tried what has been suggested which is to change the settings in the INPUT & VALUES screen, page 2 where “Vehicle Speed IS SET TO GPS”. but this still doesn’t work and I can’t seem to get any GPS reading for the speed. Does any other input work for this? Cheers