Hello! We are investigating Masteriyo and have set up a site (WP6, PHP7.4). Using Chrome for admin. Getting same 505 error message and content as above (except with ver=1.5.3). Running with ALL other plug-ins deactivated. Problem ONLY with Courses > Add new course. Goes to correct screen, then there is a noticeable delay (varies 1-5 sec) before displaying the 505 error with the same TypeError message. Once the 505 is shown, it is necessary to touch something outside of Masteriyo to clear the error. Side note: in Firefox, I get a 505 “TypeError: r.avatar_urls is undefined” with same details as noted.
Any suggestions?