diff --git a/src/Menus.cpp b/src/Menus.cpp
index 65865833f..07a0cc1c9 100644
--- a/src/Menus.cpp
+++ b/src/Menus.cpp
@@ -7822,7 +7822,6 @@ void MenuCommandHandler::HandleMixAndRender
    WaveTrack::Holder uNewLeft, uNewRight;
    ::MixAndRender(
       tracks, trackFactory, rate, defaultFormat, 0.0, 0.0, uNewLeft, uNewRight);
-   tracks->GroupChannels(*uNewLeft, uNewRight ? 2 : 1);
 
    if (uNewLeft) {
       // Remove originals, get stats on what tracks were mixed
@@ -7845,6 +7844,9 @@ void MenuCommandHandler::HandleMixAndRender
       if (uNewRight)
          pNewRight = tracks->Add(std::move(uNewRight));
 
+      // Do this only after adding tracks to the list
+      tracks->GroupChannels(*pNewLeft, pNewRight ? 2 : 1);
+
       // If we're just rendering (not mixing), keep the track name the same
       if (selectedCount==1) {
          pNewLeft->SetName(firstName);
diff --git a/src/effects/Effect.cpp b/src/effects/Effect.cpp
index 068e27e99..0259094f1 100644
--- a/src/effects/Effect.cpp
+++ b/src/effects/Effect.cpp
@@ -2537,13 +2537,14 @@ void Effect::Preview(bool dryOnly)
       mixLeft->Offset(-mixLeft->GetStartTime());
       mixLeft->SetSelected(true);
       mixLeft->SetDisplay(WaveTrack::NoDisplay);
-      mTracks->Add(std::move(mixLeft));
+      auto pLeft = mTracks->Add(std::move(mixLeft));
+      Track *pRight{};
       if (mixRight) {
          mixRight->Offset(-mixRight->GetStartTime());
          mixRight->SetSelected(true);
-         mTracks->Add(std::move(mixRight));
+         pRight = mTracks->Add(std::move(mixRight));
       }
-      mTracks->GroupChannels(*mixLeft, mixRight ? 2 : 1);
+      mTracks->GroupChannels(*pLeft, pRight ? 2 : 1);
    }
    else {
       for (auto src : saveTracks->Any< const WaveTrack >()) {