Bug - Monowire doesn't scale up in level

[LonecatPawstar]

The monowire does not seem to scale up in level as other cyberware (mantis, gorilla) do.

So the damage of the monowire remains low, and it is impossible to purchase a new monowire (Cyberware can only be purchased once).

 

[X-Fab]

Same problem here.
I got a Legendary Monowire at level 8 in a chest (in a garage) while doing a Gig in Watson (Shark in the Water) and this cyberware didn't scale its damages whereas I was gaining levels.
It stays capped at 200 damages while rare and epic monowires saled by Ripperdocs are beyond 300 damages. And like you said, it's impossible to buy another Legendary Monowire.

I also got 2 Legendary Mantis Blades in chests while doing other sidequests (Cyberpsycho and assault in progress) and they also doesn't scale their damages. But unlike Monowire, I can buy another Legendary one at Ripperdocs.

Maybe a solution for you is to grab the Legendary Monowire in Watson if you didn't get it yet (at level 50 so that it's at its full power).