Fixed pagging issue on group aggregator

src/Plugin/ExternalEntities/DataAggregator/GroupAggregator.php

@@ -980,6 +980,7 @@ class GroupAggregator extends DataAggregatorBase implements DataAggregatorInterf
           $client_start,
           $client_length
         );
+
         if (1 <= $this->getDebugLevel()) {
           $this->logger->debug(
             "Current number of entities loaded: @entity_count\nClient @client_number (@client_id)\nClient start position: @client_start\nClient length: @client_length\nLoaded: @client_entity_count",
@@ -993,6 +994,7 @@ class GroupAggregator extends DataAggregatorBase implements DataAggregatorInterf
             ]
           );
         }
+        $client_start = 0;
       }
       else {
         if (1 <= $this->getDebugLevel()) {