diff --git a/assignment-client/src/avatars/AvatarMixerSlave.cpp b/assignment-client/src/avatars/AvatarMixerSlave.cpp
index 64f4aa6821..d874100ca2 100644
--- a/assignment-client/src/avatars/AvatarMixerSlave.cpp
+++ b/assignment-client/src/avatars/AvatarMixerSlave.cpp
@@ -453,6 +453,13 @@ void AvatarMixerSlave::broadcastAvatarDataToAgent(const SharedNodePointer& node)
             // or that somehow we haven't sent
             if (lastSeqToReceiver == lastSeqFromSender && lastSeqToReceiver != 0) {
                 ++numAvatarsHeldBack;
+
+                // BUGZ-781 verbose debugging:
+                auto usecLastTimeSent = destinationNodeData->getLastOtherAvatarEncodeTime(sourceAvatarNodeData->getNodeLocalID());
+                if (usecLastTimeSent != 0 && startIgnoreCalculation - usecLastTimeSent > 10 * USECS_PER_SECOND) {
+                    qCDebug(avatars) << "Not sent avatar" << *sourceAvatarNode << "to Node" << *destinationNode << "in > 10 s";
+                }
+
                 sendAvatar = false;
             } else if (lastSeqFromSender == 0) {
                 // We have have not yet received any data about this avatar. Ignore it for now
diff --git a/libraries/avatars/src/AvatarHashMap.cpp b/libraries/avatars/src/AvatarHashMap.cpp
index cb14d7ef41..0c7054424f 100644
--- a/libraries/avatars/src/AvatarHashMap.cpp
+++ b/libraries/avatars/src/AvatarHashMap.cpp
@@ -280,6 +280,10 @@ AvatarSharedPointer AvatarHashMap::parseAvatarData(QSharedPointer<ReceivedMessag
 
         return avatar;
     } else {
+        // Shouldn't happen if mixer functioning correctly - debugging for BUGZ-781:
+        qCDebug(avatars) << "Discarding received avatar data" << sessionUUID << (sessionUUID == _lastOwnerSessionUUID ? "(is self)" : "")
+            << "isIgnoringNode = " << nodeList->isIgnoringNode(sessionUUID);
+
         // create a dummy AvatarData class to throw this data on the ground
         AvatarData dummyData;
         int bytesRead = dummyData.parseDataFromBuffer(byteArray);