Explanation
The change feed is a log of changes that are organized into hourly segments but appended to and updated every few minutes. These segments are created only when there are blob change events that occur in that hour.
Instead catch the triggered event, so move the photo processing to an Azure Function triggered from the blob upload.
Reference:
https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blob-change-feed
https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blob-event-overview