I finally got a chance to send my Sims to a flea market. Everything worked as it should. There was an NPC vendor selling at the one table. My Sim used the other table to sell his items and his wife sold paintings on the wall. All went according to plan. I'm very thankful this has been fixed! Thank you to everyone who confirmed this issue and helped test it!
Can't believe this is like 5 years ago? I have this exact issue now! I have the latest update of the game now in 2022. It went exactly as how you all describe it.
My sim (who actually lives on a lot in the city where the flea market happens) went there to sell her paintings. She put 2 paintings up and I think didn't even start selling yet, then another vendor from across the playa came immediatly. She was originally selling gemstones on a table nearby. She took over and I could not sell anymore. Instead I decided to try to sell her gems. I could actually sell at her table! No one purchased though. When it was over, the vendor left my paintings and I could reclaim them, but only after the event was over! They appeared back in my inventory... Very strange and I hope it gets fixed.
