diff --git a/core/server.js b/core/server.js
index 1e86672..8855e9d 100644
--- a/core/server.js
+++ b/core/server.js
@@ -340,7 +340,9 @@ export async function createPithos(opts = {}) {
   const autoFlush = createAutoFlush({
     settings: () => {
       const p = readPrefs(configFile);
-      return { enabled: p.autoFlush === true, minutes: p.autoFlushMinutes ?? DEFAULT_MINUTES };
+      // On unless the user turned it off: files left in the buffer otherwise
+      // never reach Sia, and nobody expects to have to push them.
+      return { enabled: p.autoFlush !== false, minutes: p.autoFlushMinutes ?? DEFAULT_MINUTES };
     },
     // Only an s3d that is up can be asked; a stopped one just means no flush.
     stats: () => (daemon.state === 'starting' || daemon.state === 'stopping'
diff --git a/ui/app.js b/ui/app.js
index d807cc4..00bbf0e 100644
--- a/ui/app.js
+++ b/ui/app.js
@@ -255,6 +255,7 @@ function overview(main) {
   main.append(
     h('div', { class: 'page-head' }, h('div', {}, h('h1', {}, 'Overview'), h('p', { class: 'muted' }, 'Your s3d gateway and its upload pipeline to Sia.'))),
     banners,
+    pendingBanner(),
     h('div', { class: 'grid two' }, daemonCard, statsCard),
   );
 
@@ -1285,6 +1286,33 @@ function siaAccountBlock(a, onRefresh) {
       'The same phrase approved from two different logins makes two different accounts; the same phrase from the same login is the same account, even on another computer.'));
 }
 
+// "N files are waiting to upload to Sia" with Upload now. s3d holds small
+// uploads until about 40 MB has built up; until then they exist only on this
+// computer, which is easy to miss.
+function pendingBanner() {
+  const el = h('div', { hidden: true });
+  const st = daemonState();
+  if (st !== 'running' && st !== 'external') return el;
+  Promise.all([api('GET', '/api/stats'), api('GET', '/api/autoflush').catch(() => null)]).then(([x, af]) => {
+    if (!x?.pendingObjects) return;
+    const n = x.pendingObjects;
+    const when = af?.enabled
+      ? (af.dueAt ? `They go up by themselves in about ${Math.max(1, Math.ceil((af.dueAt - Date.now()) / 60_000))} min if nothing new arrives.` : `They go up by themselves after ${af.minutes} min with no new uploads.`)
+      : 'They go up only when about 40 MB has built up, or when you upload them now.';
+    const btn = h('button', { class: 'btn primary small', onclick: async () => {
+      btn.disabled = true; put(btn, h('span', { class: 'spinner' }), ' Uploading…');
+      try { await api('POST', '/api/flush'); toast('Your files are on Sia'); el.hidden = true; }
+      catch (e) { fail(e); btn.disabled = false; put(btn, 'Upload now'); }
+    } }, 'Upload now');
+    put(el, h('div', { class: 'banner info' },
+      h('span', {}, h('strong', {}, `${n.toLocaleString()} file${n === 1 ? '' : 's'} (${fmtBytes(x.pendingSize)}) waiting to upload to Sia. `),
+        h('span', { class: 'small' }, `Until then they are only on this computer. ${when}`)),
+      btn));
+    el.hidden = false;
+  }).catch(() => {});
+  return el;
+}
+
 // The Accounts card at the top of the navigation: which Sia account this is
 // and how much room it has left. Refreshed at most every 30 s as pages change.
 let navAccountAt = 0;
@@ -1331,7 +1359,7 @@ async function bucketList(head, body, user, userSel) {
     h('div', { class: 'row' }, userPicker(userSel), h('button', { class: 'btn primary', onclick: create }, 'New drive')));
   const card = h('div', { class: 'card' }, h('p', { class: 'muted' }, 'Loading…'));
   const bar = h('div', { class: 'view-bar' });
-  put(body, bar, card);
+  put(body, pendingBanner(), bar, card);
   const base = `/api/s3/${encodeURIComponent(user)}/buckets`;
   let mode = viewMode('drives', 'icons');
   let list = [];