Multi person booking not referencing availability

I have a number of services which have multiple staff/resources allocated. They are set to 'Assign all of your staff for a selected appointment' which should reference the calendar of each and the default scheduling policy of either the staff or the service and only offer slots in which everyone is available within these.

I noticed yesterday when making some tweaks that the slots available are not correctly referencing the staff or service availability. This was not always the case, it used to work fine for the past 18 months at least.

An example;

Service 1 (a 1 hour slot) has me and one other resource allocated. My availability is set within Bookings as Mon-Fri during my normal working hours and is set to reference my personal calendar for availability, the other resource (a piece of equipment with an email address) is set as available all day, every day in order to cover multiple timezones for other staff bookings.

If I access the booking page today (Friday 12.30) and select Service 1, the next available date and time shown is incorrect as tomorrow Saturday at 23.30, and then Sunday from 00.00 all the way through to 22.30 - I am not available in these time slots, and my settings are definitely set correctly. The service is also set to not be bookable unless staff are free.

If I look at the next day on the booking page - Monday - there are no slots available, because I have an all day event in my calendar, so correct. Move on to Tuesday and  a small number of slots are available as I already have events in my calendar, again correct. Move onto Wednesday though, and the availability for bookings starts at 00.00 all the way through to 23.30, but this time avoiding times when I have an existing event in my calendar.

There is then the same repeated all-day, all hours availability but the next Saturday it switches back to not available at all again, but resets back to available from 00.00 on the next weekday.

Something is not working correctly, and I have tried without success to fix by;

• Creating a new service to see if there was an error in the original
• Adding new staff to see if it is a problem with my calendar
• Changing, saving then changing back service settings
• Changing, saving then changing back my availability settings

Any other suggestions? Are others seeing the same behaviour?