Embedded Sharepoint List - Custom Forms not loading

Hi Community,

I have customized the Forms of a list in my Sharepoint Online sitecollection (NewForm / EditForm and DisplayForm) with the use of PowerApps. 

These customized forms work well when opening the list in a browser.

But unfortunately, when I access the list with the Teams "Sharepoint" app, I can see the list data, but the custom forms are empty.

Sharepoint in Browser:

Teams:

Do you have an idea how I can solve this?

Thanks in advance!