FWIW, myself and another user recently lost pairing without updating firmware so it may not even be related.
You can read my remote pairing (or, lack of) rant here:
One of the most frustrating things about Tablo I’ve encountered. I would’ve bought at least 1 maybe 2 additional 4 tuner units if this nonsense hadn’t dampened our original interest.
btw, I’m only “liking” your post as a show of support and camaraderie. Not that I “like” your unfortunate situation/position.