My 1.6 diesel 2017 has central locking from the key.

The driver's door will fail to lock or unlock intermittently. The car thinks it is locked/unlocked and the alarm works as normal.
All other doors work.
I can use the key and manually it will always lock/unlock the drivers door and trigger the central locking and alarm.

So I suspect a mechanical failure with a component that physically engages the lock.

Any suggestions on this and or changing it?

I've just had a very similar problem:

The lock button on the key fob operates all the central locking actuators except the drivers's door but the alarm doesn't work, as when the drivers's door is opened it doesn't sound.

Problem only showed up yesterday, is changing the actuator a DIY job or better left to the experts?

2 hours ago, SwallownAmazon said:

I've just had a very similar problem:

The lock button on the key fob operates all the central locking actuators except the drivers's door but the alarm doesn't work, as when the drivers's door is opened it doesn't sound.

Problem only showed up yesterday, is changing the actuator a DIY job or better left to the experts?

Try locking and leaving it a few minutes before opening the drivers door. The alarm seems to have a delay.