Resetting to default settings did the trick
The issue was due to the fact that the Start Menu's setting 'Search public folders' was not ticked.
I don't use at all the default user profile location (%UserProfile%) and put all my files into a custom location (outside %UserProfile%).
And at first, I thought that 'public folders' was related to %Public% (C:\Users\Public), so I excluded it.
Maybe 'Search public folders' could be renamed to reflect the actual behavior.
Anyway, it's working now. Thank you !