Sorry for didn't reply, I didn't think someone will answer.
This began to happen months ago when I have to fill a captcha to enter to Poloniex. Everytime I enter to Poloniex I have to do a captcha.
If time happens, like 2 minutes, I have to do another one. I tried on every browser. Chrome, Chrome incognito, Mozilla, Opera, Internet Explorer, each one on their last version.
I even tried different computers with different Internet connection. I began to think it has to do with the country where I live. The only place where I can see market history is on the mobile version and I don't have to do captchas.