Reboot Optics Causes immortality on enemies, they won't die even when they are 1 HP left.
Ping and other quickhacks on legendary Tier causes frames to reduce from 60 to 15 fps.

Ultimate hacks (specifically Cyberpsychosis) bugs when I shoot the enemy while they are affected, causing them to become immortal, works fine if I don't touch em.

I have no problems with frames dropping lower when using hacks (have every hack on ultimate, including ping).

But sometimes the game plays the sound as if I'm still in the hack interface, which surpresses telephone calls and such. Caused a heap of problems with my save, basically all my fixer calls are bugged and I get a random one (of a side quest I did before but received no call) when arriving at a side quest, not the one that should play.

I have the same problem. Playing on Xbox series X. I crafted legendary quickhacks at level 20. frame rate drops and enemy becomes unkillable.

End game is the game being pulled from the store.

I'm having the same problem on PC, when I use legendary Ping quickhack my fps goes from 60 to 10-15fps. When I use other quickhacks like fade2black, cyberpsychosis or eletric damage (don't remember the name) the enemy becomes invincible, stays at 0% HP and don't die.

This is happening to me too. I was wondering why enemies suddenly weren't dying. Frustrating with a stealth-hacking build. Can't really continue the game like this.

EDIT: Upon further investigation, this seems to be related to having the legendary Sonic Shock quickhack equipped. My legendary quickhacks worked fine right up until I equipped legendary Sonic Shock. Even legendary Reboot Optics still doesn't break enemy HP, unless I have legendary Sonic Shock also equipped.

EDIT 2: I requipped my legendary Sonic Shock and got the invulnerability bug to happen again, then unequipped it and the bug stopped. I haven't been able to reproduce the framerate drops yet, but I do believe this to be the cause of the enemy immortality.