I have attached a minimal Org Mode setup that replicates this problem. The files are minimal-org.el and test.org. The lisp file is the minimum configuration for org-mode and the org-file is a simplified test file.

The minimal configuration assumes:

• A working directory of ~/tmp/tags-test when it sets org-agenda-files
• The Git Checkout of Org-Mode is located in ~/.emacs.d/el-get/org-mode/lisp

Additionally, the minimal configuration has the troublesome agenda command both as one block in a Block Agenda and listed separately as its one agenda command. (My “real” environment uses this only in a block agenda so I was covering all bases).

In each of the two cases below I have started Emacs with:

/Applications/Emacs.app/Contents/MacOS/Emacs -Q -l ./minimal-org.el test.org

Non Working Test Case:

• Switch to Org-Mode HEAD

  
  cd /Users/mike.mclean/.emacs.d/el-get/org-mode
  git --no-pager checkout master
  make clean
  make autoloads
  

• Launch Emacs as Above
• Note the two version strings from message buffer

  
  GNU Emacs 24.1.50.1 (x86_64-apple-darwin, NS apple-appkit-1038.36) of 2012-05-20 on bob.porkrind.org
  Org-mode version 7.8.10 (release_7.8.10-579-g372948 @ /Users/mike.mclean/.emacs.d/el-get/org-mode/lisp/)
  

• M-x org-agena followed by t
• Org Agenda Buffer contains just the following

  
  Headlines with TAGS match: +Outcome+PRIORITY="A"+LEVEL=4-{.*Backlog$}
  Press `C-u r' to search again with new search string
  

• M-x org-agena followed by b
• Org Agenda Buffer contains just the following

  
  Headlines with TAGS match: +Outcome+PRIORITY="A"+LEVEL=4-{.*Backlog$}
  

Working Test Case

• Switch to Org Mode version just prior to Commit c50f0c

  
  cd /Users/mike.mclean/.emacs.d/el-get/org-mode
  git co c50f0c~1
  make clean
  make autoloads
  

• Launch Emacs as Above
• Note the two version strings from message buffer

  
  GNU Emacs 24.1.50.1 (x86_64-apple-darwin, NS apple-appkit-1038.36) of 2012-05-20 on bob.porkrind.org
  release_7.8.09-33-g0ebeb
  Org-mode version 7.8.09 (release_7.8.09.33.g0ebeb)
  

• M-x org-agena followed by t
• Org Agenda Buffer contains the following (note that the correct Level 4 outline item is selected)

  
  Headlines with TAGS match: +Outcome+PRIORITY="A"+LEVEL=4-{.*Backlog$}
  Press `C-u r' to search again with new search string
    test:       WIP [#A] Level 4 - should be in agenda         :noexport:Outcome::
  

• M-x org-agena followed by b
• Org Agenda Buffer contains just the following

  
  Headlines with TAGS match: +Outcome+PRIORITY="A"+LEVEL=4-{.*Backlog$}
    test:       WIP [#A] Level 4 - should be in agenda         :noexport:Outcome::