John,Thanks for providing your setup details. I have tried with various settings on my D800 (i.e. in CMD with built-in flash in M, TTL, --Group A with TTL, AA, MChannel 1)and the SB-800 in TTL, Used Group A The SB-800 fired every time. I also tried with group A set to -- and obviously the SB-800 did not fire (which is the expected result).Did you try to do a complete reset of your D800?
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