URL Signature Expired
At times, you may notice that your Instagram posts' thumbnails don't load and remain as grey boxes. If this ever happens and you see the error...
URL Signature Expired
... this may be happening because URLs for Instagram images and videos expire after some time. Although not all URLs expire after the same amount of time, they eventually all do.
Spotlight resolves this by fetching new URLs when a feed update is run (manually or automatically via cron), so you should never see any broken images or videos in your feeds. This feature was implemented in version 0.5.3, so if you are facing this problem and using an older version, please update the plugin, fetch new posts for that feed from the Actions in the Feeds list, and check whether the issue has been resolved.
If the issue persists for any reason, please contact support for further help.