Unable to exclude traffic from an IP or a range of IP addresses

I just installed Piwik and wanted to exclude an IP address. Unfortunately there is no input field for anything.

I went to Admin > Websites and selected the site. There is a headline for excluding IP address and also an explaning text on the right, but no input field.

It’s the same with parameters to exclude?

Is there something I have to configure or what am I doing wrong?

Did you try to click where the input field would be? Maybe some browser-plugin is changing piwiks css, making the fields invisible for you? Check with your browsers Inspector in the Developer Tools.