@Leinad Abasllari, Thanks for posting in Q&A. Based on my checking internally and on my lab, I find the same issue. it is because the store apps for kiosk mode is only pulling eligible apps from legacy store named windows store for business app which is already deprecated. This is not for the store new app. So we will see the error message. You can feedback in the following link to see if we can get this in the future.
https://feedbackportal.microsoft.com/feedback/forum/ef1d6d38-fd1b-ec11-b6e7-0022481f8472
As a workaround now you can try Multi-app kiosk and add the app via Win32. Thanks for your understanding.
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