I have an airplane, and I added some seats to it and did a livery, I then saved it as a model of Roblox. The updates appeared in-game, and the thumbnail has changed. I then noticed that I didn’t anchor the livery, so I then went back into studio, took at my plane, and it doesn’t have the updates on it. I then went on the model, un-copylocked it, and took it, then went into My-Models, but it didn’t have the updates either! I don’t understand what is going on.
Have you tried updating the model again after a while?