Cannot open any files in File App due to security restrictions

All of a sudden I can‘t open any MS Office files or pdf from the file app anymore. Everything works fine if I open the files from Onedrive, where they are located. If they are on iCloud, it doesn‘t work.

The message I get with Office: „Your organization does not allow you to open this data here.“.

Running iPad OS 13.2.3 on an iPad Pro 12.9.