diff --git a/js/channelProfile.js b/js/channelProfile.js
index e8e4935d..b6e59fe4 100644
--- a/js/channelProfile.js
+++ b/js/channelProfile.js
@@ -1,7 +1,7 @@
 // js/channelProfile.js
 
 import { nostrClient } from "./nostrClientFacade.js";
-import { convertChannelEvent, buildChannelVideoFilters, loadCachedChannelVideos, saveCachedChannelVideos } from "./channelProfileVideos.js";
+import { convertChannelEvent, buildChannelVideoFilters, loadCachedChannelVideos, saveCachedChannelVideos, mergeChannelVideoSources } from "./channelProfileVideos.js";
 import { dedupeVideos } from "./utils/videoDeduper.js";
 import { DEFAULT_RELAY_URLS } from "./nostr/toolkit.js";
 import { subscriptions } from "./subscriptions.js";
@@ -5440,7 +5440,7 @@ async function loadUserVideos(pubkey) {
       return;
     }
 
-    const videos = buildRenderableChannelVideos({ events, app });
+    const videos = buildRenderableChannelVideos({ events: mergeChannelVideoSources(events, getCachedChannelVideoEvents(pubkey)), app });
     saveCachedChannelVideos(pubkey, videos);
     const rendered = await renderChannelVideosFromList({
       videos,
diff --git a/js/channelProfileVideos.js b/js/channelProfileVideos.js
index 766d8f3b..669d9d02 100644
--- a/js/channelProfileVideos.js
+++ b/js/channelProfileVideos.js
@@ -28,6 +28,33 @@ export function convertChannelEvent(entry) {
   return sharedConvertEventToVideo(entry);
 }
 
+// Reconcile a fresh live fetch with already-known events (the in-memory video
+// store + persisted cache) so a transiently-failing relay can't SHRINK the grid.
+// The channel render replaces the container with the live set, so rendering only
+// what this load fetched drops any video whose sole relay timed out — the "some
+// of a creator's videos are missing" bug. Union the two by event id (live wins on
+// collision since it's the freshest copy); the caller's dedupe-by-root + access
+// checks still handle versioning, deletes, and precedence downstream.
+export function mergeChannelVideoSources(liveEvents, knownEvents) {
+  const byId = new Map();
+  const extras = [];
+  const add = (list) => {
+    if (!Array.isArray(list)) return;
+    for (const entry of list) {
+      if (!entry || typeof entry !== "object") continue;
+      const id = typeof entry.id === "string" ? entry.id : "";
+      if (!id) {
+        extras.push(entry);
+        continue;
+      }
+      if (!byId.has(id)) byId.set(id, entry);
+    }
+  };
+  add(liveEvents); // live first → wins on id collision
+  add(knownEvents);
+  return [...byId.values(), ...extras];
+}
+
 // ---- Per-channel persisted cache (instant cold-load paint) -------------------
 // Mirrors the main feed's optimistic cache: on a cold hard-refresh of a profile,
 // render the last-seen videos from localStorage BEFORE relays connect, then the
diff --git a/tests/channel-video-merge.test.mjs b/tests/channel-video-merge.test.mjs
new file mode 100644
index 00000000..82acf29a
--- /dev/null
+++ b/tests/channel-video-merge.test.mjs
@@ -0,0 +1,52 @@
+// Regression (#20): the channel grid render replaces the container with the live
+// fetch, so a transiently-failing relay produced a smaller set and previously-
+// known videos vanished ("some of a creator's videos are missing"). The live
+// fetch must be unioned with already-known events so the grid never shrinks.
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import { mergeChannelVideoSources } from "../js/channelProfileVideos.js";
+
+const ev = (id, extra = {}) => ({ id, kind: 30078, ...extra });
+
+test("union is a superset of both live and known events", () => {
+  const live = [ev("a"), ev("b")];
+  const known = [ev("b"), ev("c"), ev("d")];
+
+  const merged = mergeChannelVideoSources(live, known);
+  const ids = merged.map((e) => e.id).sort();
+
+  assert.deepEqual(ids, ["a", "b", "c", "d"], "all unique ids from both sources");
+});
+
+test("a known video missing from the live fetch still appears (the bug)", () => {
+  // The live fetch this load only returned one video; the other is known in
+  // memory (e.g. from a prior load / the main feed). It must not disappear.
+  const live = [ev("only-live")];
+  const known = [ev("only-live"), ev("dropped-by-slow-relay")];
+
+  const merged = mergeChannelVideoSources(live, known);
+  const ids = merged.map((e) => e.id).sort();
+
+  assert.deepEqual(ids, ["dropped-by-slow-relay", "only-live"]);
+});
+
+test("live wins on id collision (freshest copy)", () => {
+  const live = [ev("x", { created_at: 200, source: "live" })];
+  const known = [ev("x", { created_at: 100, source: "cache" })];
+
+  const merged = mergeChannelVideoSources(live, known);
+  assert.equal(merged.length, 1);
+  assert.equal(merged[0].source, "live", "live copy must win the dedupe");
+});
+
+test("preserves id-less entries and tolerates non-array / junk input", () => {
+  const live = [ev("a"), { kind: 30078 /* no id */ }, null, "junk"];
+  const merged = mergeChannelVideoSources(live, undefined);
+  const withId = merged.filter((e) => e && e.id === "a");
+  const withoutId = merged.filter((e) => e && typeof e === "object" && !e.id);
+
+  assert.equal(withId.length, 1);
+  assert.equal(withoutId.length, 1, "id-less event kept, not dropped");
+  assert.deepEqual(mergeChannelVideoSources(null, null), []);
+});
diff --git a/todo/TODO_2026-06-20_pre-launch.md b/todo/TODO_2026-06-20_pre-launch.md
index 0923a7c5..3616c99c 100644
--- a/todo/TODO_2026-06-20_pre-launch.md
+++ b/todo/TODO_2026-06-20_pre-launch.md
@@ -267,7 +267,15 @@ un-hides when WebTorrent flips green). The real gaps:
 ### 20. Feed / grid loading reliability — some videos missing (BUG)
 Two related intermittent symptoms; likely the same root cause (a one-shot,
 all-relays-settle fetch that drops slow-relay results — see 17d).
-- [ ] **Profile / Channel page sometimes doesn't pull in all of a creator's videos.**
+- [x] **Profile / Channel page sometimes doesn't pull in all of a creator's
+      videos.** Root cause: `loadUserVideos` rendered ONLY the live fetch, which
+      REPLACES the grid — so when a relay holding a video transiently failed this
+      load, that video vanished even though it was known in memory/cache. Fixed by
+      unioning the live events with already-known events
+      (`mergeChannelVideoSources`, live-wins-on-id) before render, so the grid is a
+      superset and never shrinks; existing dedupe-by-root + access checks still
+      handle versioning/deletes. Regression: `tests/channel-video-merge.test.mjs`.
+      (Streaming/first-relay-wins UX is still the 17d follow-up.)
 - [ ] **Paginating between video-grid pages sometimes doesn't pull in all videos.**
 - [ ] Audit the channel/search/grid fetch for: relays that EOSE late being dropped,
       pagination cursor gaps, dedup discarding valid items, and cache-vs-live