Issue with editing content

Yesterday, I added a page to the test blog, and today when I open the editor for that page,

to make changes, I see nothing

as if I hadn't entered anything yesterday, yet the page is still present on the site,

even when you save the empty input window - the page I entered yesterday is displayed.

Of course, I could delete it and re-enter, but that's...

what could be the issue?

Drupal 7 platform