If you sign into lightroom.adobe.com in a web browser, do you see the expected photos there?
If you sign out and back in on LR iOS and LR on your desktop, does this unblock sync?
Does the Lightroom web app I mention above say anything about Sync Issues? An album called Sync Issues may appear on our web site that does not exist in the other client apps--if you see this, what are some of the errors you see on top of thumbs in Sync Issues? Typically, the suggested fix is to delete what seems stuck in Sync Issues, and re-import.
If none of these ideas seem to help, are you sure the images actually imported into Lightroom? Whatever wasn't fully imported into Lightroom will not be able to sync either. Maybe try re-importing?