Mick
That's great, thanks for the clarification.
Would it have been difficult to post a note on the forum to that effect, as soon as it was realised there was an issue?
e.g.
Forumites; We detected today that a combination of two different actions has inadvertently stopped non-logged in users seeing the forum.
We are working on it and will keep users informed
Followed with similar, short notes, keeping the forum in the loop.
Even; "Sorry, still working on it, no change", is still good communication.
Would that have been so difficult?