I’m not able to reproduce this. Is this on a new dashboard or were you updating an existing dashboard?
If you were editing an existing dashboard, make sure to actually apply the background settings when you open it up for editing. The ‘force refresh’ feature is relatively new (<2 months), so while it will default to ‘true’ in the settings UI if it wasn’t already explicitly set, that setting won’t exist on older dashboards and thus the default setting won’t be applied until you actually tap the Apply button when editing your dashboard background settings.
If that doesn’t help, I would need more details on your setup.
That depends on how things are setup. If the background is set to a URL on your Hubitat Hub that dynamically determines which image to display (perhaps via a redirect?), then you would want to make sure you have appropriate logs in the Hubitat app and that you are reviewing the logs there.
If the Hubitat app redirects to an existing image URL path and your browser already has that final image path cached, then you won’t see the logs for the requests at the final image source (eg. NAS) since the browser would load the final image from cache.
Again… this really depends on the details of how you have things setup.