Lr Device tab add vs 'add-photos'

I did some checking with Lr mobile iOS v10.3.0 and found the following behaviour with cloud sync:

• Files do not sync: in Lr mobile, click 'Device' tab, choose a photo, click 3 dots in top right corner, Organize>Add-to, pick an album. Lr indicates the file is uploading, but it never completes. Now flip to the 'Lightroom' tab, the image appears in the Album (that you added to) on the device, select the photo and observe the cloud status - still shows uploading. I left it for ages (>30 mins), and it didn't complete. The photo never appears in the cloud, therefore it won't show up in LrC, nor Lr from the desktop or any other device using Lr mobile. I checked across desktop, iPad and iPhone (where my test image started).
• Files do sync: in Lr mobile, click 'Lightroom' tab. Select the desired Album, or All Photos. Now click 'add photos' from the bottom right icon, choose 'Device', select a picture, press 'Add'. Observe the sync status for this file, once upload is complete check your other devices. Voila, the photo is sync'd.

This appears to be a bug in Lr mobile, or maybe the behaviour for Device>Organise>Add-to is not supposed to also add-to the cloud (although it shows 'uploading')?

See attached screenshots.