Error while loading recipe prototype "s6xtele-nauvis-factory-floor" (recipe): Key "icon" not found in property tree at ROOT.recipe.s6xtele-nauvis-factory-floor.icons[1]
Modifications: Telogistics

This is an odd error. What other mods are you using?

Based on the error code, my assumption would be that this is related to Factorissimo 3. I am using that mod and getting the same error.
https://mods.factorio.com/mod/factorissimo-2-notnotmelon

This has been fixed.

If you're using Factorissimo, you won't be able to build teleporters inside of factory buildings. Unfortunately, this doesn't feel quite as plausible as not being able to build rocket silos indoors, but the reason in terms of game mechanics is the same: the factory insides are their own surfaces and it would be a mess to support.

Awesome, thank you! And that limitation makes sense.