Same, immortal after the "transmission" mission on ps5. Have been through the mission twice and happened both times. Both times were different though.
On the first try, after waking from the ice bath, both me and the enemies were immortal. Quick hacks did no damage, melee weapons did no damage, grenades did no damage, but surprisingly, a smart submachine gun was the only way I could deal damage. I received no damage and kept a full health bar which continued after the mission.
On the second try, after reloading a save from 2 hours before, the enemies all took damage normally. As did I, until my health bar reached zero. Then I was immortal. I tried to use stims to keep my health from dropping to zero but they don't do anything and after the mission I still have zero health.