Hi, I actually had a sililiar issue a few days back on a page. It did seem to loop the page somehow and yes, UM was responsible for this loop. I found the error here:
When a page is missing and not being translated to this loop can occur. For me it happened cause Logout page was missing in the secondary WPML language.
So make sure all pages that UM created exist in all languages, otherwise this can happen. Good luck!