Weird central locking issue

Hi, if I try and unlock the car using the key in the passenger side it only unlocks the passenger side front door and the driver side rear door
If I lock the car on the passenger side it only locks that door and no other.
If I unlock the car using the driver side door, all doors are unlocked and it will also lock all doors.

Any thoughts about the weird behaviour on the passenger side locking/unlocking?

Its also worth noting that my remote locking hasn't worked for years, since before I bought the car. I don't know why it doesn't work but it itsn't a flat frob battery...

97 GhiaX 2.0