Mozilla Firefox word cursor not visible when editing page

Steps to reproduce
1. Create any page with any content, preferable several new lines so that the word cursor location is more obvious
2. Save the page
3. Edit the page afterwards

Expected behavior
Word cursor will appear before the first letter of the page content.

Result
The word cursor is not visible anywhere in the body content. You can still modify and add words, but it will be hard if you do not know where is the word cursor currently pointing at.

Workaround
Hover your word cursor to the page title first. Word cursor appears. Hover back to the body content to have it visible again.