Search (Ctrl+F) ceased to work

Ctrl+F opens the search window. But the search is frosen to the folder My pictures and the search criteria to Filname and contains. I can specify freely the filename and the search is then perfect. But it is impossible to specify a different folder or another criterium, for instance dates or tags. Or a search specification different from contains.

This is new, it has always worked perfectly before. And a clean reinstallation does not help.

What can I do?