For anyone having this problem if you haven't found a fix yet, one thing that worked for me was going to one of the locations that also connects to the area where the table is, like if it's in the courtyard outside of an apartment, or at a festival area where you have several apts and buildings connected. For me I fixed it by traveling to each location around the table, and pausing immediately. Upon doing so the table was free and I was able collect it again, even got some extra items as some NPC's added to the table somehow.
I will warn that this only worked once, AND when I swapped location, one of my Sim's roommates was actually tending it suddenly, but either way it worked and got my stuff back. So this is so far the only option I've found and I haven't read every post in this so sorry if I'm repeating someone. But I can verify this at least worked once. The trick is to try and get to it when no one is tending to it. Also everything stored inside was still available too. So I didn't lose anything, and I as I stated, actually gained a little.
I should also note that mine happened because I started a sale and set a sim to tend to it, but then called the sim off to talk to someone but forgot to end the sale, and that's when an NPC swooped in and stole it. Also, humorously, even tho NPC's were selling my stuff, I was still getting the money. Weird.
EDIT: Okay, spoke too soon. I decided to test this again so I reloaded a save, which still had the table taken over, and once I went to clear the table, it wouldn't clear the stuff the other sims added, so got lucky the first time but now it doesn't seem to work so...hit or miss I guess, or I got a new bug. Either way, still try this but, man, this is frustrating.
ALSO EDIT: Okay okay, now I've read through the rest of the comments and see this is supposedly fixed, it's not, but if you still have this problem, I have fixed my above problem of being unable to remove NPC sims's items...just buy them and clear the table and it's all yours again.
CM Edit - Hiya, I've moved your post here from the older thread as it was from 2017.
