Storyline 360 PowerPoint import doesn't work

Hello, 

i am using Storyline 360 and when i'm trying to import a PowerPoint .pptx file i get an error message (look attachment).
A colleague of mine is also using Storyline 360 and she was able to open the exact same PowerPoint .pptx files. We both have the .pptx files to import/open saved locally on our desktop.

When clicking the link displayed in the error message i'll get passed forward to a website with different solutions, but none of the following worked for me: 
1. The presentation is not password protected
2. I have the full version of PowerPoint
3. PowerPoint is on the newest version
4. Both softwares run on the same security level
5. The presentation starts with file 1
6. I tried re-installing Office but i still wasn't able to import any .pptx file.

I also tried re-installing Storyline 360 but that didn't work either.

I have looked trough the forums but didn't find a solution that worked for me - could someone please help me? 

With friendly regards,
Una Ponsold