I don't know why, but I have a Logitech G MX518, and this doesn't work all the time. I assign Mouse Button M4 to activate mission control, but for some reason i

I don't know why, but I have a Logitech G MX518, and this doesn't work all the time. I assign Mouse Button M4 to activate mission control, but for some reason it doesn't do anything when I click it. I tried assigning M5, still nothing. It used to work normally, pre-Mojave. Any idea what's going on?