Custom Themes not able to repeat for further editing

Have been finalising our custom invoice theme. In doing so have copied the whole file html from one theme to a “New Theme” (With an alternative name), then “Created” and when I look at the “View” there is nothing. I then go back to “Edit” the New Theme and find the html file hasn’t been saved? I wanted to make the second version in order to ensure I still have the original, when I then go to edit the second version. Version is 18.7.6

Could you upgrade to the latest version (18.7.32)? I think this bug has been fixed a few days ago.

Well done and thanks. Can now work on finalising our new Sales