The note preview is just spinning and never loads. What's wrong?

Usually this is the first-time fetch-and-convert of a large multi-page note, which can take around 15 seconds. The app has a safety timeout: if a conversion gets stuck it stops it, automatically retries once, and if it still fails it shows an error rather than spinning forever. If you see an error, check the note isn't enormous and that the device stayed reachable; closing and reopening the preview, or clicking refresh, tries again cleanly.