Auto upload of photos in My Cloud Android not working

I have MyCloud set to automatically back up photos and videos. The MyCloud app appears to detect when new photos are present and try to upload them. If I look in the “Activity” section of the MyCloud Android app, the new photos are listed with “In progress.” However, the photos never actually upload and nothing appears on the NAS drive. I’ve re-installed the My Cloud app, rebooted the NAS, tried both local Wi-Fi and LTE connections, but nothing works. What is going on?

Let the App run in the background and simply wait. Initial uploading of my +600 pictures on my Android lasts one hour using Wifi connectivity.