Mouse Wheel Zoom No longer Working

I noticed this morning I can no longer zoom in/out with my mouse wheel, whereas yesterday it was working fine. This is occurring in BricsCad v 17.2.9 and 16.2.10 (I tried v 16 thinking it was just an issue in v 17, but that's not the case). I switched to a different mouse and experienced the exact same problem, and both work fine in other programs. I also tried adjusting system variables such as ZOOMWHEEL (which I now understand only reverses the wheel action), ZOOMFACTOR AND MBUTTONPAN, among others, with no change in ability to zoom via the mouse wheel. Are there other settings I may have accidentally changed or that I'm missing that would turn the ability to zoom with the mouse wheel off? Thanks.