diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -1304,7 +1304,11 @@
 }
 
 function threadMemberHasPermission(
-  threadInfo: ServerThreadInfo | RawThreadInfo | ThreadInfo,
+  threadInfo:
+    | ServerThreadInfo
+    | RawThreadInfo
+    | ThreadInfo
+    | MinimallyEncodedRawThreadInfo,
   memberID: string,
   permission: ThreadPermission,
 ): boolean {
@@ -1312,6 +1316,9 @@
     if (member.id !== memberID) {
       continue;
     }
+    if (member.minimallyEncoded) {
+      return hasPermission(member.permissions, permission);
+    }
     return permissionLookup(member.permissions, permission);
   }
   return false;