This is very difficult to explain.
I have a factory that I think probably qualifies as late game. Most models are loaded. There are a large variety that are being cycled through the production line via schedule.
In every model I am using autosteer headlights. Low end tends to be normal, with xenon and LED at higher end, and some models have automatic headlights, which appear to just involve a sensor.
I have predictive stock control on on my fit lights slot, but turning it off doesn’t affect this.
I have two of these slots and cars go into one or the other as they see fit.
The fit lights slot has autosteer headlights, automatic headlights, xenon headlights, and LED headlights upgrades, as well as some robots.
If I click on one of the “fit lights” slot and watch it, I often see “requirements” when a car is not present as 4 normal autosteer headlights, a sensor, and 4 “normal” xenon headlights. While the car is coming, the inventory system madly tries to meet these requirements.
When a car comes down the belt eventually the requirements change, and those xenon lights aren’t required, but if it takes long enough for a car to get there, those 4 vanilla (non-autosteer) xenon lights are in the local slot stockpile, taking up 1/4 of the available space.
In the components list in efficiency statistics, there have been no vanilla xenon headlights used, so nothing is using them, and I just went and verified that in every case my car models are using autosteer headlights, so it doesn’t appear that something is wanting to use them but isn’t present yet.
I can’t figure out why the slot idles with those four xenon headlights in the requirements list. I’m reporting this as a bug because it may be causing extra importer traffic, stockpile clogging, and subsequent unavailable materials problems.
I have a screenshot if you want it.