When have trains gone missing?

There is a movie called closely watched trains which is humorous but not relevant.

It sounded nice

Well….

https://www.cbc.ca/player/play/2675415775

Perhaps they went missing when it was cloudy?

From the article: "trained to locate the sources of electromagnetic emissions with wavelengths ranging from roughly 2 meters down to 2 centimeters"

These types of signals wouldn't be obscured by clouds, presumably.

wouldn't some IR go through clouds? I thought that was the point of using IR.

That being said, the more important question is, how's the temporal resolution.

Yes. These systems are for control, not general purpose law enforcement.

Not yet

These systems are generally never used to solve low-level crimes. When they are, parallel-construction is used to avoid publicizing their existence. These systems are reserved for direct threats to national interests.