https://bugs.winehq.org/show_bug.cgi?id=45148
--- Comment #25 from odzinic@gmail.com --- (In reply to Glow from comment #24)
If someone is still experiencing this issue, it's as easy as this command line:
xmodmap -e "keycode 37 = Control_R"
Found on https://www.reddit.com/r/linux_gaming/comments/92ijwf/ cant_assign_left_control_or_left_alt_in_overwatch/
I originally made that thread on Reddit and have been using that for the past several months. It does fix the issue but it flips the control buttons on the keyboard when I use Remmina to remote in to other computers. It's a nice temporary trick but not really a fix.