diff --git a/PanTS-Demo/src/routes/Homepage.tsx b/PanTS-Demo/src/routes/Homepage.tsx
index 251367c..c548ba8 100644
--- a/PanTS-Demo/src/routes/Homepage.tsx
+++ b/PanTS-Demo/src/routes/Homepage.tsx
@@ -37,6 +37,7 @@ type FacetData = {
 	counts: Record<string, FacetRow[]>;
 	unknown: Record<string, number>;
 	total: number;
+	datasetCounts: Record<string, number>;
 };
 
 // Filter groups whose available values are discovered from /api/facets (not hardcoded).
@@ -287,6 +288,7 @@ export default function Homepage() {
 				counts: data.facets ?? {},
 				unknown: data.unknown_counts ?? {},
 				total: data.total ?? 0,
+				datasetCounts: data.dataset_counts ?? {},
 			});
 		} catch (e) {
 			console.error(e);
@@ -725,6 +727,7 @@ export default function Homepage() {
 											onClick={() => toggleMulti("dataset", opt.value)}
 										>
 											{opt.label}
+											{countBadge(facetData?.datasetCounts[opt.value] ?? null)}
 										</button>
 									))}
 								</div>
diff --git a/PanTS-Demo/src/routes/VisualizationPage.tsx b/PanTS-Demo/src/routes/VisualizationPage.tsx
index d8cd741..2e928f4 100644
--- a/PanTS-Demo/src/routes/VisualizationPage.tsx
+++ b/PanTS-Demo/src/routes/VisualizationPage.tsx
@@ -341,7 +341,10 @@ function VisualizationPage() {
 				return;
 			}
 			const id = pantsCase ?? "1";
-			const p = getPanTSId(id);
+			const isCvCase = String(id).toUpperCase().startsWith("CV");
+			// getPanTSId produces a garbage value for CV ids, but it's only used in the HF
+			// fallback URLs which are never reached for CV (CT is always on the JHU server).
+			const p = isCvCase ? "" : getPanTSId(id);
 			const localCt = `${API_BASE}/api/get-main-nifti/${id}.nii.gz`;
 			const localSeg = `${API_BASE}/api/get-segmentations/${id}.nii.gz`;
 			const hfCt = `https://huggingface.co/datasets/BodyMaps/iPanTSMini/resolve/main/image_only/${p}/ct.nii.gz?download=true`;
@@ -354,7 +357,14 @@ function VisualizationPage() {
 			// full res when ?hd=1. HuggingFace fallback is full res only.
 			const resParam = isHd ? "" : "?res=low";
 			setCtUrl(localOk ? `${localCt}${resParam}` : hfCt);
-			setSegUrl(localOk ? `${localSeg}${resParam}` : hfSeg);
+			// CancerVerse cases have no masks yet — /api/get-segmentations returns
+			// {"masks_available": false} (JSON, HTTP 200) which hangs the nifti loader.
+			// Skip the seg URL entirely so the viewer opens CT-only without hanging.
+			if (isCvCase) {
+				setSegUrl(null);
+			} else {
+				setSegUrl(localOk ? `${localSeg}${resParam}` : hfSeg);
+			}
 		};
 		resolveSources();
 		return () => { cancelled = true; };
diff --git a/flask-server/api/api_blueprint.py b/flask-server/api/api_blueprint.py
index 5583141..ddd31be 100644
--- a/flask-server/api/api_blueprint.py
+++ b/flask-server/api/api_blueprint.py
@@ -1871,12 +1871,17 @@ def _minmax(series: pd.Series):
             if len(yr):
                 year_min, year_max = int(yr.min()), int(yr.max())
 
+        dataset_counts = {
+            "PanTS": int(len(DF)),
+            "CancerVerse": int(len(DF_CV)) if DF_CV is not None else 0,
+        }
         return jsonify({
             "facets": facets,
             "unknown_counts": unknown_counts,
             "age_range": {"min": age_min, "max": age_max},
             "year_range": {"min": year_min, "max": year_max},
             "total": int(len(df_now)),
+            "dataset_counts": dataset_counts,
         })
     except Exception as e:
         return jsonify({"error": str(e)}), 400