Problem with the Transfer market and players

I was involved in trading. I bought players, resold them with a small markup in order to earn money and ran into a problem, after a while, after purchasing the players, they were added to my team, but with the note - NOT FOR SALE! It turns out that I bought them for money, but I can’t sell them. I’ll answer right away, I don’t use any programs or bots, I did everything manually! I traded first on a Playstation, then through a mobile application on my phone! Has anyone encountered such a problem? How to solve it?