Maybe the chain is on backwards. Ok, I know that sounds insane (and it might well be) but bear me out for a second. Given that depending on your riding style, you are unlikely to spend your time evenly distributed across the entire cassette, the chain will certainly spend more time at one particular angle. Now, given the nature of the chain, this angle may cause asymmetrical wear. Given that asymmetrical wear, installing a chain backwards might give you just the wrong amount of flex, and make you throw a chain.

I might be insane, but there is an easy solution, which is the only reason I post, just reinstall the chain with the plates that are currently facing inside flipped to face outside. It'll only take a few minutes, and who knows, it might work.