Issue Summary

When users attach JPEG files (under 15 MB) to Trello cards, some of the attachments fail to generate preview thumbnails. The issue is intermittent: some attachments on the same card generate previews successfully, while others do not, despite being similar file types and sizes.

Logs indicate that the attachment preview generation request is intermittently timing out, which appears to be the root cause of the missing thumbnails.

Steps to Reproduce

1. Open any Trello card in a board.
2. Add multiple JPEG attachments to the card (each < 15 MB).
3. Wait for attachment previews to generate.
4. Observe the list of attachments and their thumbnails.

Expected Results

All valid JPEG attachments should generate preview thumbnails reliably within a reasonable time (e.g., a few seconds).

Actual Results

• Some JPEG attachments under 15 MB don't generate preview thumbnails at all.

• Other attachments on the same card do generate previews as expected.

• Backend logs show that the attachment preview generation requests for the affected files are intermittently timing out.

Workaround

Currently there is no known workaround for this behaviour. A workaround will be added here when available