Ideas
Apologies for a second post, but I wanted to be sure this was seen.
I conducted an experiment that worked:
On a generic lot, containing an all-purpose building, I placed sports day and science day market stalls. (I never knew these existed until now!) Each of my two Sims hired a vendor, each of whom went to tend a stall.
Separately, at the two stalls, each of my Sims bought a corn dog. The purchases went through, an invisible item was placed on the counter (lol), and my Sims went to sit separately nearby, where each ate the invisible corndog.
As they finished, the empty plate materialized in each Sim's hand, and each disposed of it as Sims do, "tossing" it aside as it vanished in midair.
So there's that, if this is any help for playing or for fixing an issue. :)