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Unfortunately, I have no way to know what causes the issue. I am also unable to test the custom function at the moment.
You need to debug the function and try to track down the issue. First thing you need to check if the function is being triggered at all. To make sure that the hooks mentioned in the tutorial ( wpuf_add_post_after_insert ) are still available. Otherwise, you need to find out which are the new hooks.
If the function fires you need to debug it and find out at which point it fails. Before geocoding, after geocoding and it might be that the geocoding fails for some reason. You can also debug the geocoder function to see if an error message is returned from the geocoder in case that geocoding fails.