I am also getting this error.
I have been successfully using the EOS Dev Auth Tool for months. Randomly now, I am getting an error that says “Incorrect response. Please refresh the page.” when I am trying to login. This message occurs after a security check captcha pops up, which I normally don’t see.
I have the latest version of the EOS SDK, and have tried deleting the EOS_DevAuthTool folder under /AppData/Roaming/
When logging in to the EOS Dev Portal online, I am able to login successfully. I have also tried using multiple accounts.