The most likely reason is that the text editor module isn't
loading in your browser, can you see the Rich Text formatting options
shown below?
If not, save any changes and close your browser.
Reopen the browser ( either Firefox or Chrome are recommended.)
Ensure you are logging into your software using https:// secured login.
Go
to the property and edit the listings, if the editor is still not
loading reload the page and the editor should load and be available to
edit.