diff --git a/src/app/(app)/collection-map/page.tsx b/src/app/(app)/collection-map/page.tsx
index 76f245d..ed58557 100644
--- a/src/app/(app)/collection-map/page.tsx
+++ b/src/app/(app)/collection-map/page.tsx
@@ -339,8 +339,13 @@ export default function CollectionMapPage() {
     setLoading(true);
     try {
       const pb = getPocketBase();
-      const dayStart = `${date} 00:00:00`;
-      const dayEnd = `${date} 23:59:59`;
+      // Build a UTC ISO 8601 day window. `assigned_at` is stored at
+      // "YYYY-MM-DDT00:00:00.000Z" (see /api/v1/collection-map/items/[id]/assign),
+      // so the bounds need the same "T" and trailing "Z" or string
+      // comparison puts `T` (0x54) before the space (0x20) and the bound
+      // excludes every real row.
+      const dayStart = `${date}T00:00:00.000Z`;
+      const dayEnd = `${date}T23:59:59.999Z`;
       // Union of:
       //   (a) assigned items whose assigned_at lands on the picked date,
       //   (b) un-dated pool items (collection_pool + empty assigned_at) so
@@ -394,7 +399,7 @@ export default function CollectionMapPage() {
       // Also collect items whose suppliers have NO coordinates — show in
       // the sidebar so the operator knows they exist but can't be mapped.
       const unmappedRows = (await pb.collection("order_items").getFullList({
-        filter: `(item_status = "assigned" || item_status = "collection_pool") && ((assigned_at >= "${dayStart}" && assigned_at <= "${dayEnd}") || assigned_at = "" || assigned_at = null)`,
+        filter: `(item_status = "assigned" || item_status = "collection_pool") && ((assigned_at >= "${date}T00:00:00.000Z" && assigned_at <= "${date}T23:59:59.999Z") || assigned_at = "" || assigned_at = null)`,
         expand: "purchase_order.supplier",
         fields: "id,purchase_order",
         $autoCancel: false,