Appointments+ is not recording transactions

Hi there, appointments+ is not registering transactions through paypal -- thus not sending out confirmation emails or anything. It makes all appointments "pending" despite payment going through successfully.

When pending appointments are approved manually, the confirmation emails go out.

We previously used Formidable Pro to receive emails + payment for appointments and then booked dates and times manually. When the Formidable plugin is disabled, we see this shortcode in the Make An Appointment page that was generated by Appointment+ --

[formidable id=7]

I'm not sure how that got there and I can't seem to edit it out -- and I don't know if that's causing the problem. Any ideas on how to fix this or what's causing it?