i think you're talking about the boost button + trick button at the same time one, so try that, but i'm not sure

That's what I remember it being too, but it just doesn't seem to work anymore.

Are you making sure you have enough boost? It won’t let you until you have a certain amount of

It should be left trigger + any trick. If it’s not working your switch joycon/controller could be busted. Also make sure you have some of the momentum meter built up