Hi there,
this little app here:

This is a new element I created by pressing that + icon on the left, when I press the "save"-button it doesn't work and debugging gives me the error text on the right, translated: Network error while using the patch-function: The field "PowerApsId" is necessary.
By the way, I splitted the whole screen on the right into 3 forms, because it's easier to handle the different column counts.
P.S.: Whenever I edit an already existing element, a data card for example, it does nothing but switches the changes back to the original.
The excel sheet is on a sharepoint, maybe it has something to do with the user rights?
This is the error message I get, if I want to save an new element in the preview:

Translated to:
Can't be saved. Check for errors in the form.
Any ideas?