Reported on reddit:
Just had a run with 2 friends in online co-op on PS5. We made it to the third level and Crystal bot decided he didn't want to move anymore lol. We tried sending him to a new slot and also getting him to mine a crystal but he never moved from his original slotted area. We saved, closed game, and reloaded but he still wouldn't budge when we continued the playthrough.
The only noteworthy thing was we had a really good run with crystals. We probably used 7 crystal upgrades on him by that point. Don't know if that contributed to the issue. Hope a dev can look I to this for the future. Thanks!
Firstly I love your game! Just thought it might be worthwhile to report this.
During a run I needed to be able to move crystal bot to a new room to unlock the adjacent doors to progress.
Crystal bot will not leave its current slow when I stand on the new slot and ask it to move there or when I ask it to follow me directly. It is still possible to re-slot crystal bot in the same slot but they will not move away from it.
If this ever becomes a big enough issue that video would help I did record a little example video just showing all the ways I tried to get it too move.