On the EVA SAUA Post, someone and I had the issue with BR trans-pacific B class, getting this error when using United miles:

"Your paid booking class is not eligible for upgrades."

Obviously B class should be eligible to upgrade. And some other routes with BR can still be upgraded, without the error.

Has anyone seen the same? I don't really have other airline miles (NH or AV) so cannot test whether it is BR-side issue or UA-side issue.