I'm in the same boat with Bittrex.

They disabled my account just because. No explanation, no replies (except automatic, one second after, replies) whatsoever.
Several months ago I tried to do the Enhanced Verification and it would always fail for whatever reason and with a cryptic weird message so I only had basic verification.

I always tried to keep my coins outside exchanges but with the increase of the value of Bitcoin and with a deposit from Nicehash, my account was pushed above the USD $1000 and they locked it.
Now they just read the tickets, mark them as "Solved" without replying or doing anything.
I already sent them the requested selfie holding the ID, a piece of paper with the letters "Bittrex" and the date. Nothing.

And I don't live in a 3rd world or war ravaged country, so the "it's only Iranians" or "it's only Syrians" argument doesn't apply to me.

Live and learn. Even though $1,000 is a nice bunch of money, at least it didn't cost me $10,000 to learn that Bittrex can't be trusted.