After migration I see my files and folders in Finder and Spotlight but cannot access them from Ms-Office

I migrated using Migration Assistant to my new MacBook Air M3 macOS 14.5 (23F79)

I see all files and folders using Finder, although they are shown in light grey (in all folders except in Downloads and Desktop, where they are shown in black as normal). See screenshot example. I can open them as well from here and find them through Spotlight.

However when I open a 'Open' or 'Save' dialog from Ms-Office, I don't see my files and folders (except Downloads/Desktop). In Documents I only see 'Microsoft User Data' but not my own files and folders.

See second screenshot.

I looked at System Settings/Privacy and Security/Files and Folders --> there I see several applications but not Microsoft Office and I cannot add any application neither.

I re-activated Ms-Office (I can save to Documents folder), so that's not the issue.

I use iCloud.

I looked at other issues on this forum but couldn't find this exact issue.