Default sidebar categories

I just did the following on a test site earlier before responding to this other topic:

  1. Added a category #foo that is only visible to the group @foo
  2. Added the #foo category to default sidebar categories
  3. Clicked “Yes” to apply historically
  4. Logged in as “Frank”, a user who is not part of the @foo group.
  5. Verified they do not see #foo in their sidebar
  6. Added “Frank” to the @foo group
  7. Refreshed the page in Frank’s window
  8. Verified they do see #foo in their sidebar
  9. Removed “Frank” from the @foo group
  10. Refreshed the page in Frank’s window
  11. Verified they do not see #foo in their sidebar

Any idea what might be different on your end?