Disregard.

Turns out I've been playing for four hours already and needed a break.

The save file wasn't a good reproduction of what I observed, and I also found a way to get what I want:

Add a wait condition for the depot ("[station] is not full"), so that the train doesn't try to immediately ...

Hello! I'm coming from my first Space Age playthrough, with no mods.

Absolutely loving the DLC so far!

What did you do?

I created an interrupt, that directs a train with some cargo to a station to sit there indefinitely.
The station is connected to the circuit network, with "Read train ...

Ah nice catch! I had checked the permissions too, as I was toggling the "Craft" permission to help out with the Lazy Bastard achievement. Must have hit that particular permission by mistake

I'm unable to insert equipment into my modular armor.

To reproduce in the attached save file:

Right click on the equipped armor


Left click on the portable solar panel to select it


Left click into one of the armor slots


There is no feedback in step three: no *womp womp* error sound, or ...