diff --git a/explorer.py b/explorer.py
index ba68769..b4bf50c 100644
--- a/explorer.py
+++ b/explorer.py
@@ -1599,10 +1599,17 @@ def build_compass_tab(db_path: str, window_size: str) -> None:
 
 
 def build_trajectories_tab(db_path: str, window_size: str) -> None:
+    print(
+        f"[TRAJ DEBUG] build_trajectories_tab called — db_path={db_path}, window_size={window_size}"
+    )
     st.subheader("Partij Trajectories")
     st.markdown("Hoe bewegen partijen over de tijdsvensters heen?")
 
     positions_by_window, axis_def = load_positions(db_path, window_size)
+    print(
+        f"[TRAJ DEBUG] load_positions → {len(positions_by_window)} windows, "
+        f"total MPs={sum(len(v) for v in positions_by_window.values())}"
+    )
     if axis_def is None:
         axis_def = {}
     if not positions_by_window:
@@ -1636,6 +1643,10 @@ def build_trajectories_tab(db_path: str, window_size: str) -> None:
         return
 
     party_map = load_party_map(db_path)
+    print(
+        f"[TRAJ DEBUG] load_party_map → {len(party_map)} entries, "
+        f"sample={list(party_map.items())[:3]}"
+    )
     windows = sorted(positions_by_window.keys())
 
     # Compute party centroids per window
@@ -1669,6 +1680,13 @@ def build_trajectories_tab(db_path: str, window_size: str) -> None:
                 float(np.mean(ys)),
             )
 
+    all_parties = sorted(
+        set(party_map.get(mp) for MPs in positions_by_window.values() for mp in MPs)
+        - {None, "Unknown"}
+    )
+    print(
+        f"[TRAJ DEBUG] all_parties (raw from party_map) → {len(all_parties)} parties: {all_parties[:10]}"
+    )
     all_parties_sorted = sorted(all_parties)
 
     # If no parties were found after mapping MPs to parties, show a helpful
@@ -2102,6 +2120,10 @@ def choose_trajectory_title(axis_def: dict, axis: str, threshold: float = 0.65)
         except Exception:
             pass
         try:
+            print(
+                f"[TRAJ DEBUG] About to render plotly chart — trace_count={trace_count}, "
+                f"banner={banner_text}, fig has {len(fig.data)} traces"
+            )
             st.plotly_chart(fig, use_container_width=True)
         except Exception as e:
             st.error(f"Trajectories rendering failed: {e}")