"make capslock an additional Ctrl" option was removed in the latest update
try changing your ~/.config/kxkbrc
:
[Layout] # ... Options=caps:ctrl_modifier # ...
By the way, I think this list of keyboard options comes either from libinput or from xkeyboard-config.
iirc one program (a game, I think) didn’t work properly when I had nocaps: the keyboard settings would allow the keybind, but it didn’t work in-game