Howdy again!
I gotta be honest,I’m not sure why the query is not working for you now. But I did streamline that query into a miniature plugin/tool a little bit back. Perhaps the plugin will work better than directly running the query? It does support various server configurations better.
Could you download, install, and activate this: tribe-extension-recurring-cleanup Then go to WP Admin > Tools. You will see a new tool listed there that allows you to type in an event ID and clears its children.
Does that work better?
Mind if I ask what events you are trying to delete this time? Is it a new one with a lot recurrences?
Cheers!
– Brook