These things are locked behind “blue” science - Chemical Science Pack. Is there a reason they are required for Train Stop, Rail Signal, Rail Chain Signal? This prevents ANY use of trains prior to getting that science.

I’m using all three of the Enchanted mods, as well as a few QoL mods, but while I don’t believe that any of the QoL mods should have any impact, I’ll list them anyway : Afraid of the Dark, Bottleneck, CleanTiles, Concreep, Discoscience, FNEI, Mining_Drones, Power Armor MK3, Squeak Through, Turret-Shields, VisionRadar, alien-biomes, aswil, bullet-trails, fireproof-bots, miniloader, op_train_speed. Everything is up to date.

I will update the mod to unlock it before the chemical science pack.
I will keep you informed when it will be fixed, normally within an hour. Do you play in factorio version 0.17 or 0.18?

It's fixed, please update the mod Enchanted Electronics.

I play 0.18.

You could have left the RGB LED’s as part of the recipe for the train signals. They are red/green tech, and it makes sense to include them. That said, I’ve not been keeping notes, but there are a lot of things that cannot be made immediately upon research, there are other items to research first. This (and the Synthetic Rubber in your other mod) are the only two so far that I’ve found that require getting to the next science pack.

Okay, I will see to put led RGB in optics technology instead of robotics, and I will also see for synthetic rubber in order to produce it before blue science.