Appointments + Appointments Are Overriding Each Other!

Hello,

Appointments + is not recognizing existing appointments and is showing time slots as available, when they are actually booked.

Navigate to https://www.rochesterpainandperformance.com/make-an-appointment/ and choose Follow Up Visit (default) from the Service drop down menu. Click on Friday May 6 and you will see there are quite a few appointments booked (for example, 9 am-12 pm). If you then change the Service type in the drop down menu to be New Patient Evaluation, it shows quite a few times as free, which actually have Follow Up Visits booked during that time frame. For example, 9 am shows as Available for New Patient Evaluation, but 9 & 9:30 are booked for Follow Up Visits.

I have tried clearing cache in the plugin settings, & deactivating Hummingbird, but neither of these troubleshooting steps help.