Hello folks!
I have the Galaxy Tab E. I had the same problem; that annoying "loading started" notification. Today, 5/23/2017, I uninstalled a few applications, testing the results after each uninstall. I discovered an application called "TalkbacK". It was not part of the Samsung suite nor part of the accessibility programs. I am unsure how this "standalone" program was installed. In the end, uninstalling this application put an end to "loading started" and it had no impact on my accessibity programs.