CoursePresentation 1.25 -> 1.26 "Optional Button Label" is missing

Course Presentation 1.25 contains the "optional button label" feature, which allows the editor to add a label to the "display as button" option for slide elements.
This was added by this pull request: https://github.com/h5p/h5p-course-presentation/pull/293

Course Presentation 1.26 does not contain/support that feature anymore.
When Course Presentations 1.25 are upgraded to 1.26 by the editor, it removes the labels that were present earlier.

Please keep support for optional button labels in Course Presentation 1.26.

Thank you.