Lock Glitch

I've been having an issue with my locking system. I have the three button remote. Sometimes it will lock and unlock fine, other times it will lock and then will not unlock via the remote and I then can only open it with the key and even then it only opens the driver door, the back doors remain double locked until the remote decides to function properly again. I get the same behavior when I lock the car with the key, sometimes it will lock and unlock great other times it will lock then when I try to unlock there is nothing. I've noticed this happens more when the car is warm or sitting outside on a warm day. What could this possibly be. Thanks!

I have the exact same issue, can anyone please help clarify why this is happening

I will dig deeper and see what I can find. Anyone's help is very much appreciated. I just don't get it. Sometimes if I stand there and hit unlock 20,000 times it'll eventually unlock.

I have the same Problem, except it happens in extreme cold.

The lock actuators are known trouble spots, typical failure is for the doors to lock then unlock immediately. Do all of your doors lock and unlock easily manually? If you have one stuck there is a good chance that is causing your problem.
A frozen lock mechanism can do this as well. Just had this one myself, passenger door was stuck in unlocked position. I removed the actuator expecting it to be frozen but found part of the locking mechanism on the handle to be corroded and stuck. Lots of solvent, lubricant and fiddling later it's fine.
There are micro switches on the locks that tell the General Module lock status, if they are bad, dirty, out of adjustment, etc. the GM will do odd things.
A broken wire in the trunk harness can also cause locking issues.
Begin by checking that all of the lock actuators are moving and all of the lock cylinders are working.
General Module and relay module failures happen too, easiest way to diagnose these is to simply swap with a known good one if available

I have the same issues but it doesn't seem to be temperature related. I locked the doors via remote and it wouldn't unlock right away so I used the key. MISTAKE! Alarm went off and continued to till I relocked the door and got them to unlock with the remote.

If one of your door lock actuators are failing or if there is a physical bend in the metal, it will hang up all of the locks.

You can sometimes see which are faulty because they lay lower in the automatic unlock position.

When you replace the actuator, you want to do it in pairs. Back seat lr or front seat lr sides.

Mine were so hung up at one point, I would unlock the car and it relocked immediately. Really pissed me off after awhile so I just said F it and replaced all of them.

Secondarily, if it's a signal issue, that can only be resolved by getting a new alarm system and swapping out the OE controller under the back seat. I bought a system from the hoffmangroup stellar security system for the E34. I paid more because it had remote start, which I use alot in hot or cold climates. There are much cheaper systems out there though. No need to go gangbusters just to unlock your damn door.

This is what I did to correct the issue. Ymmv.