I just returned from a mission and didn`t click on repair in debriefing screen.
I went into the character management screen, entered the screen with the Bionics and clicked on “repair” for the Bionics.
Had all tech and materials I needed.
But game refuses to repair the Bionic Head for me.
Annoying!!!
Don`t want to buy another head and then the old head back.
Edit:
Found a workaround: In the inventory screen you can click on Repair too. But a fix would be better.