Hi, Tim, it also happens sometimes in the text editor when replying to posts. Click to reply, the editor window opens, and the cursor isn't visible. It's there, in the first column on the first row, because you can hit any character and it'll show up. But it makes it look like something is wrong.
It's been that way for a while, but it's such a minor item that I don't think anyone really noticed.
I've seen it in both Chrome and Firefox, running on Win10.
I've suspected that it's something with the way the forum software interacts with the browser. I seen similar issues at times with our applications (I work in software development, as a QA tester). A new version of the browser is deployed, and some things in our app no longer work correctly.