I have today found out that when I'm in section e.g. "TODAY" of my workbook
and searching for all tagged items, grouping them by "tag name", even though
I _*_have selected to search all notebooks_*_ (which IMO should also include
all sections of them) that only the items of the current section appear. When
I'm changing the group by selector to "sections" then I suddenly see more
tagged items than before. When I switch back to group by "tag name" all of
them are also there, but as soon as I hit "refresh results" I'm down to those
items in the current section only.

So short summary: Searching for tagged items only shows items from the
current section, switching the group by selector back and forth to and from
something else reveals all tagged items.

This smells like a bug to me.