Bookings calendar not displaying availability

We have a personal bookings page set up with 4 meeting types, two public and two private. None are displaying any availability, except ONE of the private ones, despite checking custom settings and ensuring there are no availability clashes or all-day events in the calendar. The one private booking type that is showing appropriate availability has both custom hours and a date-bound limit (only booking until November 6).

So the broken ones look like the Devised Theatre appointments above.

And the only one that is working is the ANTH 100 below:

Both of the above screenshots are pulling from the same calendar and availability. We were able to get the Devised Theatre one to display some availability by setting it to a custom limited date range and custom hours, then reverting it back to standard availability and no date range which seemed to preserve the availability the system found when limited, but provides no availability beyond those previously set custom hours despite having no more set limitations.

Do we have to fiddle with custom availability to "unlock" standard availability? Or is there an actual fix that would resolve this issue?