In JCE Pro 2.9.56 a Descirption field was added to the JCE Media Field so that the "alt" attribute for the image could be set. Adding the Description field required that the Media Field value be saved as a JSON string, containing values for both the URL and Description fields, ie: {"media_src":"","media_text":""} instead of a single value for the URL as before the update.

This change caused some issues for some users who were accessing the field value directly from the database in Yootheme Dynamic Content and other extension functions.

A Legacy Media Support option has been added in the Field - Media JCE plugin parameters to remove the Description text field and restore the single URL value. Once enabled, existing affected articles containing thesese JCE Media Fields should be re-saved to restore the single value.

The option can bse set in System -> Manage -> Plugins in Joomla 4 and Joomla 5 or Extensions -> Plugins in Joomla 3. Search for Field - Media JCE , click the entry to edit it and enable the option if required.