Associated article usage - event content

According to the help text, you can use a Joomla article as the main content for the event.
However, when you save the event, the title and description are written into the existing article.

Thanks for reporting this.

Saving an event should not overwrite an existing article selected as its content source.

This is corrected in the refreshed JEM 5.1.0 Beta 4 package. Keep Article updates from event set to Read-only source. Changes made to the Joomla article will still appear in the event, but saving the event will leave the article unchanged.

Please download the refreshed package from Beta versions and test again from
www.joomlaeventmanager.net/download/beta-versions

The workflow is explained in Event Content Articles.
www.joomlaeventmanager.net/documentation/frontend/events/event-detail

Please let us know whether this resolves the issue.