I put 1 Decorative Metamorphic Rock 2 in, all of the other items that don't smart stack with it, became grayed out
Then went into my gleam lantern smart stack, with 14 cream gleam lanterns, and 50 yellow, selected the yellow, and put it into the plinth. successfully.
Then i repeated the act with a smart stack of sapphires, leaves, iron grapples, compact soft coal, gem hammers, Slingbow crystals, iron hammers, healing brew, copper chisels, basic torches, stone slingbows, silver hammers, iron shovels, and regular torches.
Then when i went to remove the items after showing them, i could not put them back into the smart stacks, i had to put them into an empty inventory slot, then exit the plinth, and recombine them.
and yes, i am able to succesfully put prices on all of them, and if i do not put prices on all the items nothing can be sold. only the first item shows up on TOP of the plinth, but all are sellable.