I've not had a tea set disappear since making them able to go into a Sims Inventory. I do get the "Clean Spoiled Food" option on the sim pie menu after they've been around a while whenever they are in inventory, but none have vanished as of yet. That's not to say they still won't, but being able to stash them quickly in inventory has helped at least.
I've opted to share the change for anyone else that wants to use my mod for this until the bug is fixed. You can download the
modded tea sets here.
And, seeing as I made the mod for it, if anyone wants to be able to stash the champagne bucket as well, that is
here.
Both mods are overrides of the EA default objects, so you should be able to just remove the mod at any time that the issue is fixed. Just make sure to take any of them out of Sim inventory before removing the mod for best results.
Edit: I should mention, I also made steeping the tea cheaper, 30 instead of 90...because it was wack that it was so much more expensive per cup then the electric personal brewer.