Strange behavior with different formatting

Hi guys.

I noticed that when I want to publish a new topic, and I use several formatting options for the fonts, then select the post with the mouse or CMD + A (CTRL + A), that my text disappears and the box contracts. When I reload the page, my input appears again. But as soon as I select the text again, the box disappears. Take a look at the behavior in the video. If I keep the formatting, the problem does not occur.

I have also been able to reproduce it here in your community here..