Lightroom Classic Sync gets stuck uploading files

I often find that Lightroom Classic sync to the Adobe Cloud gets stuck uploading images.

Removing the offending images and from sync and all synced images usually clears the issue, however I can repeat the issue.

1. Add some previously un-synced images (mine are usually new imports)  to a collection and let them sync - wait for the icon to stop spinning and turn green.
2. Remove some of the images from the collection
3. Then immediately add some of those removed back into the collection

The added images just added back in to the collection just sit in an 'uploading' state. I have left them trying for hours.

I have observed on occasion that LrC will remove the newly added images from the local collection

I occasionally make a mistake and change my mind about images I've removed from collections so add them back.

I have done the above steps several times now and find the results consistent.