Using companion Cait.
In the middle of a tower fight, she wants to talk. She appears in the elevator sitting down like she needs a Stimpack but there is no option to revive her.
We complete her final story discussion, She stays sitting, I finish the boss fight, go outside.
She still sits on the ground and no revive option. Just general; Talk, Dismiss, Trade, Nevermind options.

Just a sitting Cait.

Hmm. Try recruiting another companion & send her home? Either way, if it is her last mission I've heard that some companions wont be able to be companions again. Idk.
I think some glitches are due to playing the game too long. Take a break, quit the game - go back into the game, should be fine? lol