I've come to notice a strange behavior of some of the fixtures at a property I frequent. The parking lot is lit with all led fixtures which I think are working fine. There are a couple older canopy lights at the entrances that are metal halide but most are using led bulbs.

I've noticed that before the whole parking lot light system turns on the canopy lights both led and metal halide and a few led wall packs blink on and off for several minuets before all of the lights eventually illuminate. Each flash cycle lasts for several seconds and once the rest of the lot turns on the odd behavior stops and all lights work constantly. I'm sure that the lights that are flashing are on a different circuit than the rest of the lot but they do all illuminate at the same time.

If someone has a theory of what's happening please leave a comment.

I've seen LED floodlights with PC that flashing before staying on.

Bad P/C . some of my driveway lights did the same thing a few years ago . A simple P/C swap solved the problem .

Or it may be an improper installation/alignment of the PC's, when the light from the lamp reaches back  the photocell sensor, when the daylight is "just on the threshold". It could be someone added somewhere an extra banner or so, repainted some structure (so it starts to reflect light again) reflecting the light back onto the photocell.
Most photocells are rather dumb when speaking about the light level response, with just barely a simple hysteresis and timer (does not matter if they are the old thermal relay, electromagnetic or electronic), so really rely on no light from any of the lamps leaks back to the sensing element.
To meet that condition sounds simple on paper, but sometimes it is very hard to actually achieve, mainly when the installation is in some "denser" environment (a lot of structures around, a lot of lights, mainly higher power lights). And mainly to make sure it is met even in adverse weather condition (haze, fog or dust in the air, rain, snow,...) there.