I am working on several Power Point presentations on several different desktops. When I try to access an open presentation in one particular desktop I get instantly switched to another desktop that does not contain that document. I have 6 desktops with no assignments of any apps to a given desktop.
This is actually a known problem with Microsoft apps.
I have heard that the issue is fixed in Office 2015: https://products.office.com/en-us/mac/mac-preview