gv-checkbox-bug-filter.php

<?php
add_filter( 'gravityview_entries', function( $entries, $criteria, $passed_criteria, &$total ) {
	$view_id = GravityView_frontend::getInstance()->get_context_view_id();

	if ( $view_id != 97 /** Augmented View ID here */ ) {
		return $entries;
	}

	$_subtract = $criteria;

	/** Build an inverse query on isnot operations */
	foreach ( $_subtract['search_criteria']['field_filters'] as $key => &$filters ) {
		if ( ! is_numeric( $key ) ) {
			continue;
		}

		if ( $filters['operator'] == 'is' ) {
			$filters = null;
		} elseif ( $filters['operator'] == 'isnot' ) {
			$filters['operator'] = 'is';
		}
	}

	$_subtract['search_criteria']['field_filters'] = array_filter( $_subtract['search_criteria']['field_filters'] );

	/** Find out the form IDs */
	$form_ids = array_unique( wp_list_pluck( $entries, 'form_id' ) );

	$subtract_entries = GFAPI::get_entries( $form_ids, $_subtract['search_criteria'], $criteria['sorting'], $criteria['paging'], $_total );

	$subtract_ids = wp_list_pluck( $subtract_entries, 'id' );

	$leftovers = array();
	foreach ( $entries as &$entry ) {
		if ( in_array( $entry['id'], $subtract_ids ) ) {
			$total--;
			continue;
		}
		$leftovers[] = $entry;
	}
	return $leftovers;
}, 10, 4 );