Sentinels should follow the charachter you're currently playing like Pets already do - Operator and Necramech

[16Bitman]

 When you leave your Warframe and play another "charachter" the enemies start getting aggroed to the sentinel and will very quickly take it down.

All the other companions will instead follow your operator and necramechs, making themselves much harder to kill.

 

I request that the sentinels will follow your Operator & Necramechs, so playing as something else for an extended period of time isn't instantly killing them.