The solution is to skip gnome-tweaks altogether and instead set a custom shortcut using gsettings:
$ gsettings set org.gnome.desktop.wm.keybindings switch-input-source "['<Shift>Alt_L']"
$ gsettings set org.gnome.desktop.wm.keybindings switch-input-source-backward "['<Alt>Shift_L']"
Caveat: if you have more than two layouts, this works a bit weird: Alt+Shift does cycle between the layouts normally but Shift+Alt just cycles between the last two, so be careful with how you press it. I tried variations of these commands where I switch the shortcuts around or use the same one or leave one out but couldn't find anything that doesn't behave weirdly; perhaps I haven't tried hard enough though.
Okay, the solution suggested in this gitlab issue comment fixes it for me: https:/ /gitlab. gnome.org/ GNOME/gnome- shell/- /issues/ 4511#note_ 1309852
The solution is to skip gnome-tweaks altogether and instead set a custom shortcut using gsettings: desktop. wm.keybindings switch-input-source "['<Shift>Alt_L']" desktop. wm.keybindings switch- input-source- backward "['<Alt>Shift_L']"
$ gsettings set org.gnome.
$ gsettings set org.gnome.
Caveat: if you have more than two layouts, this works a bit weird: Alt+Shift does cycle between the layouts normally but Shift+Alt just cycles between the last two, so be careful with how you press it. I tried variations of these commands where I switch the shortcuts around or use the same one or leave one out but couldn't find anything that doesn't behave weirdly; perhaps I haven't tried hard enough though.