BUG: When trying to make a walk-in reservation, some timeslots are greyed out on the calendar UI and a walk-in reservation cannot be made

[ss12430]

I was alerted by PA James that he was not able to make a walk in reservation for a reservation holder due to time on the calendar being greyed out and non-selectable:

Admin Andi also tried and experienced the same. They noted it happened in the Co Lab and Audio Lab also. I tried today and saw it on the calendars for 221 and 222