Not sure the exact issue but I have 2 motion sensor I got online, they was cheap so have a feeling this is my overall answer.
They are _TZ3000_o4mkahkc model, now I have these setup one at the top and bottom of the stairs to turn on/off an LED strip.
However, the issue seems to be after 4/5 hours roughly they just stop communicating. Stop reporting into HA and stop detecting motion, if I remove the batteries and put them back in, or press the reset button they immediately work again for a few hours?
Any ideas? Are they going to sleep? Batteries are brand new, reporting 100% and I have tried multiple ones?