Yes, I agree. A sticking plaster CSS fix is not an efficient solution. Plus the full CSS should be:
/*** hide attendees list and opt-out ***/
.tribe-attendees-list-container, .tribe-tickets-attendees-list-optout {
display: none;
}
I think that what has happened is that the update was supposed to correct all entries in the database but failed to do so. As much as I love this plugin, its updates often break sites.
Don’t hold your breath for a solution. 🙁