I struggled with this forever and I think I have a solution.  I believe using the troubleshoot button (top right next to view log button, follow the directions to download the troubleshoot app, add it, and run it.  I believe this troubleshooter must flag something in the system and everything auto fixed in about 20 minutes.  I believe a developer or some automation fixed the server side code and eventually the soap calls worked.

There is literally no other explanation as I could not even remove the application.  And it would fail over and over until I ran that troubleshooter.  I allowed the troubleshooter to only run when the company file was open.  When it prompts you for the password, enter "password" and let it save it.  I ran it a few times because it initially did not fix it, but like I said, maybe 15-20 minutes later, everything worked.