I disabled all my UI (and SIM ofc) mods and I cannot overcharge units manually. I dont know how useful a replay is, because you cant see me try to click there. https://replay.faforever.com/26505419 . I also had this issue on Sunday in Ladder matches killing me because of it.
Auto OC works, only manual targeting does not.

I thought it would have to be some of my mods because nobody else reported this problem. But that wasnt it.