I have LED lights in most of my home, but lately those in the hallway and bathroom behave weird: mostly in the morning when I wake up and try to turn the lights on in the hallway they don't work. When i try it in the bathroom the light also doesn't turn on but the bulb shines very faintly. After several minutes they suddenly turn on without me doing anything. This behaviour is not perfectly deterministic as sometimes they turn on without issues, but mostly they do not. Also after they "start working" they usually work fine for a while until I leave them off for extended periods of time.
I would like to fix this but my knowledge about electricity/wiring is almost nonexistent. It seems to me that the problem could be something small but so far any attempts at locating it/fixing it have failed. I tried removing one LED light from the hallway at a time to see if any are broken, but it happens even if I remove several/most of them or remove the bulb in the bathroom.
Relevant background about the flat:
We moved in several years ago and then did a reconstruction of basically the whole flat in three phases: first the bathroom, then bedroom and finally the kitchen, living room and the hallway. The issues began about a year after the hallway was finished. All was done by a reputable company and this is (so far) the only issue we have. As far as i know, all electricity wiring was replaced with new one, as the flat had old copper (?) wires and very few power outlets.
Some other relevant info:
The hallway and bathroom are on separate breakers. The hallway has 1 light switch at every end (so there are 2 switches for the hallway lights).
Lights in the hallway: Kanlux CT-2114 (https://www.svet-svitidel.cz/kanlux-324-podhledove-svitidlo-argus-1xgx5-3-50w-12v/?gclid=CPKZk5bZzNQCFQwo0wod6vsG7g)
Lights in the bathroom: regular Philips 9.5W LED bulb
Does anyone have an idea what could be wrong or how could I locate the issue? Thanks!