I have been using the gTile Gnome shell extension. In gTile, I defined specific preset window positions, along with the keyboard shortcuts Super+1, Super+2, etc. to apply them. This was all working fine until a recent update of Gnome. After the update, some of my shortcuts now seem to do other random things, while other shortcuts don't seem to do anything at all.
I looked in Settings → Devices → Keyboard → Keyboard Shortcuts, but the Super+1, Super+2 shortcuts didn't even seem to be defined. I also uninstalled all other Gnome shell extensions (thinking that other extensions might be setting their own shortcuts) but that didn't help.
Why are these shortcuts un-remappable and how can I make them remappable again?