Tradable player from the transfer market becomes untradable

Hi, I bought my 115 LW Barnes at the transfer market, which cost me 4.5 billion coins. When I checked my card today, I found out that my card has become untradeable. I’m absolutely sure I’ve never pressed the activate badge button or converted this card to an untradeable card, so either this is some kind of a system bug or someone has hacked into my account. How do I solve this problem? Please help