I have appointments+ set up with 2 services.

I have appointments+ set up with 2 services. Integration/sync is set up and appears to be working. Except....
When I have the first service selected, all of the previously booked slots are unavailable as they should be. However, when I select the second service - all slots are open even though they continue to be booked in GCal.

Any thoughts on what could be wrong?