Softlock warning!
If you bring umbra into a Free roam and swap directly to your Necramech, it doesn't take into account his passive. Going from Umbra to Necra does not turn ON his AI, but worse still going from Necramech straight into an AI Umbra doesn't turn OFF his AI, making him stand still and shoot things and softlock you. (Escape still works and you can evac the mission)
Figure this one warrants a /u/rebulast link.
Edit: P.S. Bonus bug, getting onto K-drive and being forced immediately off is still a bug that exists and it saddens me because I enjoy living out my Jet Set Radio warframe fantasy that Sheldon cursed me with.