Guess your app is multilingual. And the language set for development is different to the language set for the test user.
In studio pro, go to languages and check the selected language.
Next go to app, login as admin and go to account overview and check selected language of the test user.
This might be because of incorrect translation. Are you using multiple languages in your application? If yes, please go to Language > Batch Translate and see if the correct button caption is there for all the languages that you are using
Did you update the caption of the button correctly?
If so, can you delete the button re-add it once again to the page?
Can you share the screenshot if possible
Is the button visible for your user? Because the visibility is set on selected roles...