Not able to drill in SSAS connected Excel file hosted on Power BI, solvable?

Hi 

I have installed the Enterprise Gateway and SSAS reports directly in PBI works like it should.. BUT.. 

I also want to host my old SSAS Excel files on power bi and be able to use the pivot tables etc. When trying to drill down in the pivot table in the Excel file it fails. This also happens when i try to use the file directly from my OneDrive for Business folder (Excel Online). Opening it in local Excel is no problem, works fine. 

I've tried searching up and down, but its all a bit technical for me. 

How can i use/drill/refresh SSAS reports inside Excel Online/Excel Services.. ?