Collapsed-banner thumbnail still missing on 2026.9.3 after #5995 (iOS 27.0.1) #5998

After #5995 the image is shown again when the notification is expanded (with an action), but the small thumbnail on the collapsed banner is still missing. Before 2026.9.3 (on 2026.9.1) the thumbnail was shown.

Environment

• App: 2026.9.3 (2026.3126)
• Core 2026.9.4
• Reproduced on two iPhones: one on iOS 27.0.0, one on iOS 27.0.1

Payload

• data.image: /media/local/snapshots/x.jpg
• Also tried data.attachment: {url, content-type: jpeg}, same result

Behaviour

• Without actions: no thumbnail and no image when expanded (2026.9.3: image attachment not shown on a notification that has no actions (regression from 2026.9.1) #5988).
• With one entry in actions: the image shows only when expanded, with no thumbnail on the banner.

What I checked

• The attachment is downloaded: right after delivery the notification service extension authenticates and fetches the JPEG (HTTP 200, full size).
• The image is valid (2560x1920 JPEG, 320 KB).
• Two different phones show the same, so it is not device-specific.
• Because 27.0.1 also fails, a newer iOS does not seem to fix it here.

Related

• Attachment is downloaded at delivery but no thumbnail is shown on the collapsed notification #5802 and iOS 27: notification image thumbnail not showing after 2026.9.1 update #5838: same symptom, and the comments on 27.0.1 and 27.1 report the same on 2026.9.3.
• Keep the content extension for notifications with an image attachment #5995 states the missing thumbnail is an iOS 27 bug. iOS 27: notification image thumbnail not showing after 2026.9.1 update #5838 was closed after 27.0.1, but the thumbnail still fails on 2026.9.3 with 27.0.1, so the app may be involved.

Happy to provide a debug log if useful.