When I use the Side scroll wheel or horizontal scroll wheel on my mouse, then the bottom part moves, but it doesn’t function as scrolling, it doesn’t move. Look at the timestamp at the top corresponding to the bottom slider. Not moving right?
I have the same problem. I had horizontal scrolling working fine with Audacity V2.2.2. It stopped working when I installed the Logitech Options so that I could remap the mouse Back/Forward buttons to CTRL +L. I even reset to software to default, with no luck restoring Horizontal scrolling in Audacity.
It’s too bad that I can’t remap the horizontal scroll buttons to SHIFT+Scroll. I am going to uninstall the Logitech Options software to see if that will fix it.