Hi, all.
I’ve done some investigation on the incompatibilities. The biggest problem is that Bookly decides to wait until objects are destructed to persist anything to the session (See Bookly\Lib\UserBookingData and the destruct method). By that logic, and from what I have seen, the custom session handler is going to be already destroyed by the time the plugin tries to write data to the session.
As a test, I added $userData->destruct() to the Bookly\Frontend\Modules\Booking\Ajax class in the sessionSave method beneath the call to $userData->fillData( $parameters ); and the session values appear to save correctly in some instances.
I have created a small patch that resolves the problem.
I have created a small patch that resolves the problem.