When you do the Magg storyline, and get to the part where you have to “Search for magmacyte” and “Navigate the lava field with Magg.” .. if you get to it too fast, he will bug out and you get stuck on this, ending up in a dungeon that can’t be progressed anymore.
You can still get the extinguisher from him, and he still follows you, but the trigger at the Magmacyte does not work.