Hey there @miket, I apologize for the delay in response.
I understand this question was asked quite some time ago but if you are still facing this issue I would be happy to give it a look. One thing that can help our investigation is when you are experiencing the broken workflow to capture a HAR file. This would allow us to follow the Authentication flow and see where the breakdown is happening. Please be sure to select “Preserve log” to catch redirects and scrub the file of user passwords before passing it over in direct message.
Due to the age of this topic I will keep it open for another ten days just in case you have any lingering questions on this subject. Thanks!