Recently, we were tasked with updating our form themes to reflect our new branding.  When we tried to make changes to an existing theme in Designer Mode, and then tried to save the changes to the same theme name, we get the following error message:

The theme name already exists in the classic designer. Rename and save to create a new theme in the form designer.

Our workaround at the moment is to go into Classic Mode, make the changes there, and overwrite our theme, I feel like this might not be a viable option going forward.

If we could please have the ability to overwrite an existing theme in Developer Mode in a future release, that would be fantastic!