Every month I combine points from my various UR accounts (four cards, three logins) to my spouse's account. I send them all to her Freedom card, one after another, and then consolidate from her Freedom to her Sapphire Reserve.
That definitely flies in the face of my theory. That said, my workaround seems to have helped at least a few readers, so I'm ok with being wrong about the cause.
I'm curious, if you have no issues, why you don't combine directly to your spouse's Sapphire Reserve instead of the interim step to her Freedom. Perhaps it's best not to mess with something that's not broken.