[MP] Reproducible projection welding bug.
I don't know if it's MP exclusive but I can reproduce this bug, spent 3 hours on it.
Project a small ship BP that uses batteries. Weld it either by hand or large welders. After completion, DO NOT grind to disconnect. Get in cockpit, change battery state. Get out, grind connection to projector. Your ship will be stuck. Try thrusting away and see what happens.
To fix it at this stage you have to grind the batteries and rebuild.
To prevent this, after welding complete, immediately grind the connection without playing with the battery state. Then all's fine.