the rows in your client hasnt change so there are no changes to send. now you can try to do a dummy update on the client rows just to update their metadata in the tracking table(think update table1 set col1=col1).
now when you do the dummy update, Sync Fx will complain about a conflict since the row is updated on one side and the same row is deleted on the other side (most likely a
LocalUpdateRemoteDelete or LocalDeleteRemoteUpdate) .
you can subscribe to the ApplyChangeFailed event on your Azure provider to check for conflicts, then set e.Action = ApplyAction.RetryWithForceWrite to force the update.