uh...didnt the game mention that the interaction button is z? try dedicating it to another button in the games settings if it still doesnt work and try again...
if the issue still persisted, answer my comment and tell some more details about the problem and i might be able to fix it!
im so sorry for the inconvenience.
Viewing post in Empty Shift jam comments
normally this problem is because of corrupted save files not containing what key those assignments bind to
try and see if there are any files called save in this directory:
"AppData\Roaming\Godot\app_userdata\Empty Shift\saves"
if there is, delete it and open the game again
another solution could be you yourself going in options in the main menu and setting the keys up again which might work
let me know of what happens, i have to fix it if its an issue from the game!