Sounds like a case of improper measurement. Chains are made accurately enough that you should never be able to see any length difference over 12 inches, with a new chain. Place one end of the rule on the edge of a pin. The pin at the other end should be completely covered when new. After some use, the covered pin exposure increases. I have a full length measurement setup that can show small differences over 54-55 inches. Campy chains are extremely consistent. The new sram axs chains, not as consistent. I've used a Campy chain for 6,000 miles and measured very little elongation over the full length, but the roller wear was huge and the side clearances were twice that of a new chain. When a second chain was installed on the cassette, there was new-chain skip. Don't rely only on checks of elongation. Some sram axs users are reporting similar extremely low elongation, but those users will get new-chain skip too. I alternate the use of 4 chains and will never get new-chain skip.