How can I have a post ticker to display only one category of post, based on the "categories" field in wordpress post editor ?
Enable the Advanced Settings within the Ticker Type > Posts > Basic Query Settings section of your Ticker.
Then in the Advanced Query Settings > Query Args section set your Parameter to be either cat or category_name. If using cat, set the value to be the term ID of the category you wish to display. If using category_name, set the value to be the term slug of the category you wish to display.
Then be sure to update/save your ticker.
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