diff --git a/templates/partials/slm_live_view.html b/templates/partials/slm_live_view.html
index dc5e363..0779dac 100644
--- a/templates/partials/slm_live_view.html
+++ b/templates/partials/slm_live_view.html
@@ -570,14 +570,17 @@ function updateLiveMetrics(data) {
     if (document.getElementById('live-lmax')) {
         document.getElementById('live-lmax').textContent = data.lmax || '--';
     }
-    if (document.getElementById('live-ln1')) {
-        document.getElementById('live-ln1').textContent = data.ln1 || '--';
+    // Only update Ln values when the frame actually carries them. DRD stream
+    // frames omit percentiles (DOD-only), so without this guard a live stream
+    // would blank L1/L10 over the values rendered from the cached DOD snapshot.
+    if (data.ln1 != null && document.getElementById('live-ln1')) {
+        document.getElementById('live-ln1').textContent = data.ln1;
     }
     if (data.ln1_label && document.getElementById('live-ln1-label')) {
         document.getElementById('live-ln1-label').textContent = data.ln1_label;
     }
-    if (document.getElementById('live-ln2')) {
-        document.getElementById('live-ln2').textContent = data.ln2 || '--';
+    if (data.ln2 != null && document.getElementById('live-ln2')) {
+        document.getElementById('live-ln2').textContent = data.ln2;
     }
     if (data.ln2_label && document.getElementById('live-ln2-label')) {
         document.getElementById('live-ln2-label').textContent = data.ln2_label;
diff --git a/templates/sound_level_meters.html b/templates/sound_level_meters.html
index b1f0407..697f6e7 100644
--- a/templates/sound_level_meters.html
+++ b/templates/sound_level_meters.html
@@ -322,8 +322,10 @@ function updateDashboardMetrics(data) {
     document.getElementById('chart-lp').textContent = data.lp || '--';
     document.getElementById('chart-leq').textContent = data.leq || '--';
     document.getElementById('chart-lmax').textContent = data.lmax || '--';
-    document.getElementById('chart-ln1').textContent = data.ln1 || '--';
-    document.getElementById('chart-ln2').textContent = data.ln2 || '--';
+    // Guard: DRD stream frames omit percentiles, so only overwrite when present
+    // (else the live stream blanks L1/L10 over the cached DOD snapshot values).
+    if (data.ln1 != null) document.getElementById('chart-ln1').textContent = data.ln1;
+    if (data.ln2 != null) document.getElementById('chart-ln2').textContent = data.ln2;
     if (data.ln1_label) document.getElementById('chart-ln1-label').textContent = data.ln1_label;
     if (data.ln2_label) document.getElementById('chart-ln2-label').textContent = data.ln2_label;
 }