Why can't candidates see available slots when selecting an interview time?

I believe there was a BUG associated with this? I cannot seem to locate it again. We are still experiencing where the "candidates choose their time slot" from the manager's availability based off of O365 integration and their chosen time slots, they do not SEE the blocked off times that are unavailable. So, when they select a time slot, the candidate gets an error and they have to keep clicking new slots until one works for them. Below is the message they are receiving and have to continuously click until they find an available slot.

"Your interview wasn’t scheduled. Try again later".