I read your post #2 again, and caught where you did both sides at 15K. My bad. I'm inclined to go with the heat from the rearmost bearing failure melting the fitting and blocking the flow. Sounds reasonable.
When I had the oil pan off my 560, I found 2 large pieces of RTV in the oil pump screen, along with a small piece of plastic chain guide, and a larger piece of guide on the floor of the pan.
There was a big chunk of guide lodged on each side of the engine chain passageways too, each just big enough to not go down to the pan. I crazy glued all the pieces together to ensure that I had found all of them. I figure I dodged several major bullits.
You weren't so fortunate with the RTV. However, if not already done, I'd drop the pan and do a thorough investigation for additional pieces of flotsam and jettsom before they migrate up to the oilers. Just my amateur thoughts.

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1986 560SL
2002 Toyota Camry
1993 Lexus