There are typically 3 things that can cause this.
- You have shift - “yourkeybind” bound as something else in keybindings. (It sounds like you’ve already checked this.)
- You have shift set as you focus, self, or mouseover cast key in Options > Gameplay > Combat.
- You are using numberpad keys as your bindings. Windows will hijack most shift + numberpad options. The only solution here is to choose another keybinding or modifier. (Mac users can run into another problem with MMO mice, which can be fixed with the terminal.)
From your description of how its working and what you’ve tried, #2 looks like the most likely option. The priorities for those modifier options have always been a bit unintuitive (sometimes they override, sometimes they don’t) but it seems like they have changed in Dragonflight so they’re more likely to override.