Weird problem with the mouse and the TAB function

(Windows 10 laptop): This is a weird one for sure. I’ll be working away in my project, and left-clicking the mouse will oftentimes plop me to the bottom of the document. Hitting the TAB key, same thing. It isn’t the mouse: happens on different mice I’ve tried. Isn’t the laptop: this only happens on Scrivener; not MS Word, internet, nowhere else.

So I am constantly being dropped to the bottom of my doc, and having to scroll all the way back. I’ve tried to figure out if it’s a TAB setting, but as usual I can’t find anything relating to it in the worthless, non-searchable manual, or on the Internet.
Any help appreciated!

What version Scrivener are you on? (Help > About)