What are the cranks? I've had issues with 130bcd crank spiders being too large for 38t rings so the chain can't fully engage with the ring. Might be some weirdness there that's keeping the chain from wobbling on the ring to let it get to the 41.
My truvativ rolleur cranks had too much metal on the end of the spider out past the chainring bolt hole to let me run a 38t. I filed them down, but still hadn't been brave enough, so I went with a 39.
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Shimano : Click :: Campy : Snap :: SRAM : Bang