I've searched this title, there were similar issues discussed, but on older models, they do not seem to apply on 2018 RX450H models.

Symptoms: Sometimes, it works. 50-60% of the time it works.
Randomly, the power back door will not close, it long beeps.
Nothing works. I had to manually push down the trunk door to close it. and I am afraid that it is damaging the motor.
The power door does seem to open most of the time. It only stuck once.
I have tried everything: different buttons, start engine, shut engine, reset the PDR off/on, clean the struts, WD40 struts/joints.

Any ideas?