My maps were missing all their asteroid belt locations, leading to undesirable dynamic route generation. I had to methodically test Better Planets, Redrawn Space Connections, Redrawn compat, Cosmic Distancing, Outer Rim, Nexus route settings—all the mods that would reasonably be suspected of mangling a starmap.

Meanwhile the background-picture mod was doing:

if string.find(name, "background")
or string.find(name, "star")
or string.find(name, "asteroid") then
loc.hidden = true
loc.starmap_icon = nil
end

Basically:

“Oh, your destination has asteroid in its name?
Clearly that's decorative scenery. Delete it from the UI.”

And because it only hid the space-location rather than deleting the underlying routing data, the routes continued functioning, which made the diagnosis particularly obnoxious. Your platform could literally fly through the asteroid belt while Factorio insisted there was no destination there.

That is an impressively nasty compatibility bug for a mod whose job is essentially make space background prettier.