@Benjamin Kokholm Broen, Thanks for posting in Q&A. Based on my researching, I find a similar issue with this error message. For that issue, it is caused by missing scope tag. In the picture you provided, I find the scope tag is no. Please add a scope tag to this application to see if it can be saved.
Hope the above suggestion can help. If there's any update, feel free to let us know.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.