The "progress" of the Cloud Sync progress bar jumps in very big increments. Often it will be just sit on 0%, long delay, ~70%, long delay, 100%. It could be more useful. It appears the "progress" is simply a percentage of the #"tasks" (point push, point, pull, point delete, track push, track pull, track delete") completed. It would be more attractive & better diagnostics for the bar to represent to #bytes / total estimate #bytes.
I'm sure the description underneath the bar is not always correct too. On the last sync the 1st "description" was "deleting points" then a long delay. However when I checked activity there were no point delete operations, just 1 x track pull delete & 6 x track pushes - see attached screen cap.