Rear door causing all doors to lock

[Al Arming]

Hi

I’ve just bought a 2016 625 Enterprise van and have an interesting issue with it and hope someone might have an idea if it’s a fault or normal.

I unlock the van using the remote, go to the back door and open it, I then close the back door(barn doors) and ALL the doors lock! 

I then have to use remote to unlock the van, I’ve never had this on any other van I’ve had so is it normal for this model? Damn annoying if it is.

I found the positive battery connector was loose after the previous owner jump started/charged it so have made sure everything is as it should be and carried out a BSI reset but this issue remains.  If I shut the front or side doors nothing happens as I would expect. Van locks and unlock fine with the remote.

So, is this normal or is there a way of stopping it locking all the doors when I shut the left hand back door?