I hate playing with an incorrect rule. Arg!
After checking the rules, you can show all of your tiles to your opponents and restock all of your tiles from the bag (and then throw in your previous tiles) if you do not possess any tiles with the colors shown by your lowest cubes on your scoring card.
I was playing under the assumption that if you had more than one color of cubes tied for last on your scoring card that you could not swap your tiles. My rules clearly state “any of the colors” indicating that there can be more than one.