Sorry for the delay, had something come up and couldn’t work on this for a day or two. I tried running the command you suggested, however it failed as I didn’t have any offload options set on the interface.
Out of curiosity I tried enabling GSO & GRO offloading on the interface and now MSS is being adjusted properly per the config! I’m not entirely sure what combination of offload options I can/should be using, however considering this seems to have fixed my issue I’m inclined to leave it alone (unless you have other recommendations.)
Thanks for your help!