This just randomly started happening and I'm not seeing any reason why or anywhere giving me any info on what's happening (error messages? warnings? anything?). I have a Latitude E6540, but I saw another post here about a different model with the same problem (though it's unanswered and closed), so it seems to be a Dell touchpad issue.

Two-finger scrolling works everywhere else, including in the Navigation pane on the left (that has Quick Access and This PC).

Does anyone know anything about this, or how to figure out what's going on, or how to fix it or troubleshoot it?