Old tip, but always good!

This is the cure for every chain.

But apart from that, are you sure that it's not your drivetrain? I expect the Zen chainring to be round, but did you center the chainring on the cranks? Sheldon Brown

The good question is, what part of a precision manufactured chain shall break in? And why should that cause such a strong effect? Yes, chains wear out when they are in use, but that doesn't happen after a few rides. Especially not on a track bike, which neither sees water nor lots of dirt.

Put a new chain on your bike and check it out. A $10 KMC Z410 does the trick for that.

Good luck

Thomas