Can’t edit big text in visual editor

Hi!

I have problem similar to this one.

When I click to edit the content no content shows and I get the page load spinning symbol. In my case is a lot of text, over 100 kilobytes. The website is running on my company server (I’m not the admin, only maintaining content of the website).

It seems that the Wordfence blocks content loading – when I disable Wordfence’s firewall visual editor opens and loads content normally.
But I can’t use the solution given by Alex S because Wordfence’s Live Traffic shows no blocked traffic from the plugin :-/ So, is there any manual method to whitelist it in the firewall?

I can’t recreate the problem on my local home server due to diffent software and configuration – shortly, it works without any problem.

WordPress and plugins are up to date.

Robert