I only use their platform occasionally, mainly to exchange crypto for fiat. I keep a very small amount of funds on the exchange, as I primarily trade on DEXs. I no longer trust centralized exchanges (CEXs).
Are you trading with a large amount of funds in them? because if that's the sole purpose of your trade then just using them as an outlet of your trade to fiat, maybe they don't like that behavior. No one knows about that in actuality but if they're looking for more docs that you're providing and not letting you to continue, the problem is on them, and I doubt it that they're going to disclose that to you, and alani might be right that they just don't want you to use them anymore.