cannot add "content bottom" 1 & 2 in widget area

I’m new to WordPress. I started a site with 2016 theme. At first, I was able to add content to the Content Bottom options. Now, they don’t respond – I cannot click them open to edit, or move them. (I don’t remember how they are supposed to work).

Web Dorado, who make the Photo Gallery plugin, edited some code on my theme that they say were slight misspellings. This was to fix an issue where there were thin blue lines across my slideshow gallery. I didn’t edit any code myself. Wondering if there is a system-wide issue, if their edits could be the problem, or if I am just missing something silly.

Any advice greatly appreciated. Thanks in advance!