Cannot insert HTML into the page

Hello.

I've stumbled on the simplest question.

I wanted to try inserting HTML code into my page. But instead of the HTML code, its textual version is displayed. I carefully watched your lesson 2.4. Blog, CKEditor - blog on Drupal 8. I did not find any differences from my settings. Please tell me what is wrong.

Here is the page display:

http://5cm.ru/view/i7/MlH6.png

Here is the page itself, you can see that full HTML is selected

http://5cm.ru/view/i7/U3tw.png

Here are the full HTML settings

http://5cm.ru/view/i7/aoPE.png

http://5cm.ru/view/i7/1TWn.png

Actually, I tried to format one of the themes I chose and downloaded. According to its manual, you need to insert a block and put HTML code in it so that the form displays video. I realized that I cannot insert an HTML block. The form does not display the video. So I decided just to try inserting HTML into a text field. It didn't work.

Respectfully, Denis.