Trying to enable 100gb Stacking ports on N3248P-ON switches

Trying to get my new switches stacked with the 100gb stacking ports on the back. Every time that I try and change iut to a stack port, CLI states that "Stack port mode is not supported for this interface". I am able to swap it to a stack port in the GUI, save the config and reboot, does not save the change. Running switches on 6.8.1.0

Dell spec sheet confirms that these are 100gb stacking ports and I am using 100gb stacking cables:
DAC-QSFP28-100gb