thank you for the possible solution.
I have one question, if indeed is the weak or failing motor in the actuator, i would assume each of the rear doors behave differently.. but the intermittent unlock failure and working is pretty consistent.
Meaning the rear doors either unlock or not unlock, not like one works and ither doesn't.

Based on this observation i did further research and there may be a relay problem GM3 as per https://www.bmwgm5.com
which needs this unit service to replace the relay.

I had ordered the motors just incase its indeed is the actuator but appears this unit relay probably dying and might have gotten carbon corrosion on the terminals preventing it to have good contact. I had contacted Scott who provides this GM3 service and see what his diagnosis says.

Thanks for response and if i do fix actuator motor your instructions are golden as reference .. thank you