Central locking problem

[Siddy1200]

I have a 2004 E53 3.0i, it's low km and it pretty good condition. Had it a while without any issues.

Recently, the rear doors won't unlock with the central locking.
Also the lower tailgate won't unlock either.

The front doors and upper tailgate are still working fine

When I press the unlock fob button 1 time, the drivers door unlocks (as normal).
Then the 2nd press unlocks the front passenger door and also allows the upper tailgate to be opened.
But the rear doors and lower tail gate are all still locked.

I can still open the rear doors by pulling on the inside handle.

I had a similar issues with my E46, it turned out to be a common problem with the gm5 module, I replaced a relay and it was fixed. I see the E53 doesn't have a gm5 but a similar module might be the problem. There is a relay that does both rear doors but it's a seperate circuit that does the tailgate so I am confused as to what could cause this problem.

From doing a search, I see the most common problem is with the door actuators but I don't think this is my problem.

I have checked the 3 fuses that are labelled central locking.
I have disconnected the fuses for 5mins to reset the system.

Any ideas?