Thanks @WhiteNoise, wasn’t sure where to put it.
@rsdimitrov, I only see “The sidebar is empty, try dragging a pane here.”, no arrow. Did I mess something up? I have a slightly tweaked custom CSS, and I can edit the CSS to remove this, but I’m wondering if there should be an in-software solution to this, since I don’t want to edit my CSS every time I want to see tags, etc.