I just wanted to give an update. I was never able to resolve the problem with anything outlined here. Eventually I contacted premium care and they replaced my phone. I have not logged into my Samsung account on the replacement phone, and I am not having the Bixby issue on this new device.
Did you ever get this fixed, my S8+ started doing it after this most current software update in June. I have Bixby turned off, Bixby voice wakeup is off, did all resets and cache clears and nothing can fix it except I assume a software update fix from Samsung.