[Moeman]

YOUR chain has a tight spot and to make sure of that
i would adjust the chain and go for a ride if there is
tight spot you will find it being loose again

While u are it check the sprockets
front and rear for extra wear
cause a tight chain will chew
sprocket's teeth

 

[Moeman]

The tension will change at the stretched part of the chain
but you would feel the effect evreywhere while the bike
is moving

 

[Moeman]

My chain is like this too. Kinda maddening. You tighten the chain, then it gets loose. Is this something that is covered under the mfgr warranty?

You have a tight spot within your chain
warranty does not cover chain or sprockets