This issue was detected during accessibility audit on learner-facing pages in Workplace performed in August-September 2023 by AbleDocs.

The "Attendees" and "Potential Attendees" automatically update when you type into the respective search fields, but do not inform the screen reader

https://wpaccessibility402.prototype.moodledemo.net/mod/appointment/editattendees.php?s=54&backtoallsessions=4

Success criteria:
4.1.3 Status Messages:
Ensure the text feedback is given an appropriate role for a status message.
https://www.w3.org/TR/WCAG21/#status-messages

We have moved this issue to MDL project because it needs changes in the core class. The same accessibility issue can be observed in "Add/remove to groups" form