Appointments+ 1.9.4 service providers can not edit working hours

Under A+ 1.93, when a service provider was logged in they could see their "Working Hours" etc, but when they tried changing any settings (Working Hours, Holiday, or Exceptional days), the resultant screen would say "Are you sure you want to do this?", but without a confirmation button, and the page title reads "WordPress Failure Notice" (see attached).

When we updated to A+ 1.9.4, our site has stopped displaying the "Appointment Settings" page to users logged in as a service provider altogether.

The "Appointment Settings" tab appears in their profile, but stops displaying anything beyond displaying the title "My Working Hours". They could no longer manage their Working Hours, Holidays, or Exceptional days.

After rolling back to A+ 1.9.3 it's displaying the "Appointment Settings", but back to giving the error.

NOTE: we had not tried testing the "in profile" editing with earlier versions of A+, but can find out.