Hi @jurajj
This could be due to your theme or another plugin loading JavaScript on our admin pages and creating a conflict.
Can you run through our JavaScript troubleshooting guide below:
https://www.wordfence.com/help/advanced/troubleshooting/#how-to-inspect-the-browser-console
When you have the Console tab open and you see any errors can you take a screenshot and paste a link to an online image sharing service. Instructions for taking a screenshot are further down the page if you don’t know how to do that.
Also open the Network tab. Reload the page. If you click on the top of the Status column you can group by response status code. If you see any response code other than 200 or 304 can you take a screenshot and paste a link to an online image sharing service.