Have we discussed this issue before:

There is a setting to override a ‘feature’ of WP Engine hosting, that truncates long SQL queries (which ours are). Edit the site wp-config.php file and add this at the top, after line 1 (on a new line 2):

define('WPE_GOVERNOR', false);

(also see here for another related support note about this – https://support.searchandfilter.com/forums/topic/killed-query-errors-in-log/#post-64826)

I would just say though, that rather than adding this in blindly, to research and make sure this setting doesn’t adversely affect anything in your site.