Has it become impossible to include an Action button and a Choice on the same screen?
Yes. The only time you can not have an action button is if there is no graph component. So if you want to use an action button you’ll need to also add a graph.
If you just need a basic Submit button, I think those are possible with choices. Off the top of my head, you need a SubmitLabel sink in the choice component. You also need to call on it somewhere else because the button won’t show up. For example, the note component could have
content: when choice.submitted "You made a choice!" otherwise "Please make a choice."