How do you access your application (URL)? and is there a difference between going through the .mendixcloud url and custom domain url?
Often the error you receive is because the page is redirecting to different URLs again and again and again. So checking how the application is reached is important to understand the problem.
It may be worth putting a breakpoint on your Default home page microflow (and role based homepages). Single step through this, stepping into SUBs where necessary, and you’ll hopefully find where it is redirecting.