Shortcode causing error message

Hi there,
our action displayed here
https://www.blockadeaustralia.com/action/

included on the page using shortcode
[actionnetwork id=1]

Was displaying fine, now is showing this error, not displaying action
Notice: Trying to access array offset on value of type null in …/wp-content/plugins/wp-action-network/actionnetwork.php on line 609

We changed the dates of the action. Have hit ‘full API sync’ didn’t fix. I don’t think any plugins or wordpress have been updated to cause it to break…

Any clues for troubleshooting?