I implemented a digital circuit somewhat in the molds of what is shown at https://www.factorio.com/blog/post/fff-140 (the rails one).
Here, the signal at the left is red when the sum of the ouputs at the vertical gates is > 0 (ergo, any of them is open). I also use that same output (sum) signal to force the door at the left (the one the train will be facing) shut.
![Image](https://cdn.pbrd.co/images/20FCw7rw.png)
As you can see from the image above, the connected signal is signaling red, but as seen below, the chained signal back there is signaling green. Thing is: the train stops.
I tried moving the chained signal further away, then closer in, but this behaviour persists.
![Image](https://cdn.pbrd.co/images/20Fk7Mqh.png)