Leon Central Locking problem

[darkomtc]

Hello,
I'm just wondering if this may be known/common problem and can be fixed. Car is Seat Leon 2010.

So, locking always works, all of the doors lock. But if I try to unlock the car 30s after it has been locked, only drivers door unlock. If I happen to unlock car, let's say 15s after I lock, the car unlocks normally (all doors unlock).

Seems like the unlock mechanism turns off after 30s of being locked.
Funny thing is that lock mechanism works even after 30s of being locked (I can re-lock, I hear all of the doors locking again and turn signals light up).

I'm talking about key in door. The remote key fob is not original and it behaves the same way as the key in door, since it's the additional system that only gets connected to existing locking electronics.