updated 2nd query, cuz i had a bug (edited it btw)
update ubbt_USER_PROFILE SET USER_VISIBLE_ONLINE_STATUS='yes' WHERE USER_VISIBLE_ONLINE_STATUS <> 'yes'
that forces everyone to be visible..
and no, it's not really a bug. at some point in the history of your forums, you allowed people to choose to be invisible (yourself included).. they did that...
then you have now turned off that option for them to choose.
soooo, for those who are currently invisible .. they will never have a choice to make themselves visible again since there is no choice they can see..
so i'd call it a feature!