If I have a 3key binding (e.g. alt-shift-1) and 2-key binding (e.g. alt-shift), when I press alt-shift-1 it just does the alt-shift binding instead (and writes shift+1). Shorter bindings override longer ones, and I cannot find how to change it. If I change the alt-shift binding to something else like alt-ctrl, alt-shift-1 would work, but e.g. alt-ctrl-→ wont.
I'm on a fresh installation of Ubuntu 18.04 with Cinamon. This wasn't an issue on my previous installation of Ubuntu 16.04 (unless I've changed something and forgot.