diff --git a/src/slic3r/Utils/MoonrakerPrinterAgent.cpp b/src/slic3r/Utils/MoonrakerPrinterAgent.cpp
index 5e81878b29e..f33886b3c5e 100644
--- a/src/slic3r/Utils/MoonrakerPrinterAgent.cpp
+++ b/src/slic3r/Utils/MoonrakerPrinterAgent.cpp
@@ -710,27 +710,46 @@ void MoonrakerPrinterAgent::build_ams_payload(int ams_count, int max_lane_index,
 
 bool MoonrakerPrinterAgent::fetch_filament_info(std::string dev_id)
 {
-    std::vector<AmsTrayData> trays;
-    int max_lane_index = 0;
-    int active_lane_index = -1;
+    auto count_loaded = [](const std::vector<AmsTrayData>& trays) {
+        int loaded = 0;
+        for (const auto& tray : trays) {
+            if (tray.has_filament) {
+                ++loaded;
+            }
+        }
+        return loaded;
+    };
 
-    // Try Moonraker filament data (more generic, supports any filament changer
-    // software that reports lane data to Moonraker like AFC and recent Happy
-    // Hare as of Feb 15, 2026)
-    if (fetch_moonraker_filament_data(trays, max_lane_index)) {
-        BOOST_LOG_TRIVIAL(info) << "MoonrakerPrinterAgent::fetch_filament_info: Detected Moonraker filament system with "
-                                << (max_lane_index + 1) << " lanes";
-        int ams_count = (max_lane_index + 4) / 4;
-        build_ams_payload(ams_count, max_lane_index, trays, active_lane_index);
+    // Query both sources. The Moonraker lane_data namespace (AFC and recent Happy
+    // Hare as of Feb 15, 2026) is more generic, but it can be stale or only
+    // partially populated, while the Happy Hare mmu object carries the full gate
+    // inventory (or vice versa). Pick whichever source reports more loaded slots
+    // so a sparse database can't shadow a fully-populated changer.
+    std::vector<AmsTrayData> moonraker_trays;
+    int moonraker_max_lane = 0;
+    const bool moonraker_ok = fetch_moonraker_filament_data(moonraker_trays, moonraker_max_lane);
+    const int moonraker_loaded = moonraker_ok ? count_loaded(moonraker_trays) : 0;
+
+    std::vector<AmsTrayData> hh_trays;
+    int hh_max_lane = 0;
+    int hh_active_lane = -1;  // KX/stable: 3-arg signature from PR #13719
+    const bool hh_ok = fetch_hh_filament_info(hh_trays, hh_max_lane, hh_active_lane);
+    const int hh_loaded = hh_ok ? count_loaded(hh_trays) : 0;
+
+    // Prefer Moonraker lane_data on ties to keep the original priority.
+    if (moonraker_ok && moonraker_loaded >= hh_loaded) {
+        BOOST_LOG_TRIVIAL(info) << "MoonrakerPrinterAgent::fetch_filament_info: Using Moonraker filament data with "
+                                << moonraker_loaded << " loaded of " << (moonraker_max_lane + 1) << " lanes";
+        int ams_count = (moonraker_max_lane + 4) / 4;
+        build_ams_payload(ams_count, moonraker_max_lane, moonraker_trays);
         return true;
     }
 
-    // Attempt Happy Hare first (more widely adopted, supports more filament changers)
-    if (fetch_hh_filament_info(trays, max_lane_index, active_lane_index)) {
-        BOOST_LOG_TRIVIAL(info) << "MoonrakerPrinterAgent::fetch_filament_info: Detected Happy Hare MMU with "
-                                << (max_lane_index + 1) << " gates";
-        int ams_count = (max_lane_index + 4) / 4;
-        build_ams_payload(ams_count, max_lane_index, trays, active_lane_index);
+    if (hh_ok) {
+        BOOST_LOG_TRIVIAL(info) << "MoonrakerPrinterAgent::fetch_filament_info: Using Happy Hare MMU data with "
+                                << hh_loaded << " loaded of " << (hh_max_lane + 1) << " gates";
+        int ams_count = (hh_max_lane + 4) / 4;
+        build_ams_payload(ams_count, hh_max_lane, hh_trays);
         return true;
     }
 
@@ -992,7 +1011,13 @@ bool MoonrakerPrinterAgent::fetch_moonraker_filament_data(std::vector<AmsTrayDat
                                     << "' mapped_by='generic_fallback' tray_info_idx='" << tray.tray_info_idx << "'";
         }
 
-        max_lane_index = std::max(max_lane_index, lane_index);
+        // Only advance max_lane_index for lanes that actually hold filament so trailing
+        // empty lanes are trimmed. Interior empty lanes (e.g. lane 0 empty, lane 1 loaded,
+        // lane 2 empty, lane 3 loaded) stay below the highest filled index and are still
+        // emitted as empty placeholder slots by build_ams_payload.
+        if (tray.has_filament) {
+            max_lane_index = std::max(max_lane_index, lane_index);
+        }
         trays.push_back(tray);
     }