In home lens categories are automatically turned off

[vanadium]

Description: Ubuntu 14.10
Release: 14.10

unity:
  Installed: 7.3.1+14.10.20141016-0ubuntu1
  Candidate: 7.3.1+14.10.20141016-0ubuntu1
  Version table:
 *** 7.3.1+14.10.20141016-0ubuntu1 0
        500 http://be.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

unity-scope-home:
  Installed: 6.8.2+14.04.20131029.1-0ubuntu1
  Candidate: 6.8.2+14.04.20131029.1-0ubuntu1
  Version table:
 *** 6.8.2+14.04.20131029.1-0ubuntu1 0
        500 http://be.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

Seemingly randomly, categories in the home lens are turned off automatically. On a subsequent search, results from that category are not returned. When the user presses <esc> to clear the search window, the default categories are enabled again.

Opening "Filter results" in the Dash allows to follow the status of the categories.

Detailled description of the problem:

- Both my "Applications" and "Files&Folders& categories are open
- <super>projects: after a short while, many files and folders appear. however, I notice that "Applications" is being disabled.
- <super>firefox: rather than having the familiar firefox icon appear, I see a few files (that presumably have been downloaded with firefox). Indeed, even while the typing erased the previous search term, "Applications" continues to be disabled, and thus is not searched from the home lens. Pressing <esc> and then retyping the query re-enables the Applications lens again.

Expected behaviour: as soon as a new query is entered, all Categories should be re-enabled. Typing "firefox" from the home lens always should reveal the firefox icon, unless the user actively chooses to disable the Applicationa category.

I have the impression this happens when there are many results from one single category. e.g I can reproduce this typing the name of one of my folders, e.g. "Projects", under my "Documents" folder. Such a query presumably retrieves all files with "projects" in the path name. At that point, other lenses appear to be dissabled, and unfortunatelly remain disabled when the user enters a new query.