Issue with fetching records with the Year and the Month for specific sites

[Sae126V]

We're encountering an issue where accessing the URL pattern /gridsync/<SiteName>/2025-05/ works for some sites but fails for others. The behaviour is inconsistent and requires further investigation to identify the root cause.

[tofu-rocketry]

May be due to a site not having any SubmitHosts that match between the different tables.

[tofu-rocketry]

Or they're sending records that don't note a submit host.