diff -u b/src/GroupMembershipLoader.php b/src/GroupMembershipLoader.php
--- b/src/GroupMembershipLoader.php
+++ b/src/GroupMembershipLoader.php
@@ -92,10 +92,11 @@
    * {@inheritdoc}
    */
   public function load(GroupInterface $group, AccountInterface $account) {
-    if (!isset($this->userMemberships[$account->id()])) {
+    $cache_id = md5($account->id());
+    if (!isset($this->userMemberships[$account->id()][$cache_id])) {
       $this->loadByUser($account);
     }
-    return isset($this->userMemberships[$account->id()][$group->id()]) ? $this->userMemberships[$account->id()][$group->id()] : FALSE;
+    return isset($this->userMemberships[$account->id()][$cache_id][$group->id()]) ? $this->userMemberships[$account->id()][$cache_id][$group->id()] : FALSE;
   }
 
   /**
@@ -108,7 +109,7 @@
     }
 
     if (isset($this->groupMemberships[$group->id()][$cache_id])) {
-      $this->groupMemberships[$group->id()][$cache_id];
+      return $this->groupMemberships[$group->id()][$cache_id];
     }
 
     $filters = [];