Thank you for your answer
In my published report I had two excel files and one folder but I also added all three sources to the data gateway.
Now I made a fresh report with only one excel file called "JiraExport_ITS.xlsx" and published it to the app. I still get the same "error" though.
I also made sure that the "Data Source Name" in "manage gateway" is the same as the "dataset" name in the app. (I am not sure if this is neccessary or powerbi automatically should detect the connection due to the filename"
