Dear Agata,
You can check whether All User Group been assigned to any other Group other than Administrator Group where for the Group other than Administrator may be they have denied access to the Sub-folders under All Folders(Root Folder). This could be another possibility.
So kindly re-check whether All User group is part of any other group other than Administrators Group.
Note : Every user in BO Platform will be part of Everyone User Group by default.
Rgds,
Sethu.