Hi,
not sure whether that is related, but there is an error in this part of the field, try replacing in the _where function lines 170-171 as $s_field is undefined in the else part of the if clause
if ( isset( $fields[$w] ) && $fields[$w]->storage == 'standard' && $fields[$w]->storage_table == $table ) {
$v = $values[$w]->value;
with
if ( isset( $fields[$w] ) && $fields[$w]->storage == 'standard' && $fields[$w]->storage_table == $table ) {
$s_field = $fields[$w]->storage_field;
$v = $values[$w]->value;