I use a Logitech G203 mouse. It only has 2 side buttons, 3 and 4. I have them bound to mute/unmute and melee, however, I also have them bound to my keyboard due to them randomly not working while playing, then suddenly working again. There doesn’t SEEM to be any rhyme or reason to when they work or don’t. It’s incredibly frustrating to have to move my left hand all the way over to the “M” key to mute or unmute myself midgame, and even mid-fight.
I’ve looked at a few things about mice side buttons not working and it’s all about binding, which I am certain is not the issue.
Also, as I primarily use the side buttons in OW, I am not sure if they turn on and off any time else. I only notice it in OW.
Any feedback is appreciated. Thank you 
The first thing to try for this sort of issue is to check if there is an update to the software for the device. You can also try uninstalling the software and then installing a fresh copy of it.
If the above does not work then try the steps below.
Logitech peripheral key-mapping is controlled by SetPoint.exe .
- Ensure the latest version of SetPoint is installed: SetPoint – Logitech Support + Download
- Exit any open Blizzard programs.
- Open Task Manager (Ctrl-Shift-Esc).
- Locate SetPoint.exe in the running applications. End the task.
- Locate SetPoint.exe in the file manager.
- Right-click and select Properties .
- Select Run this program as an administrator.
- Click Apply and OK.
- Launch SetPoint.exe.
Hello, after a week and a half vacation I did a thorough test of what you suggested to me, I took about a week of playing and trying to uninstall and reinstall and a few other things including the SetPoint.exe, which… I’m not sure it… did anything.
I still have the exact same problem as before, where the 2 side buttons on my mouse randomly do not work at all for minutes at a time, then suddenly working again for a few minutes. No rhyme or reason, has nothing to do with being in or out of games or any other factor that I can notice.
I ALSO tried a few other things about generally a mouse button not working and nothing worked either. I’m at a complete loss and don’t have the money to spend on another pricey mouse. If you have any suggestions at all, even something that sounds silly, I’m willing to listen. Thank you!
Try uninstalling G-HUB, unplugging the mouse, and installing the legacy Logitech Gaming Software instead.
https://download01.logi.com/web/ftp/pub/techsupport/gaming/LGS_9.02.65_x64_Logitech.exe
Once installed, plug the mouse back in, but on a different USB port that’s directly on the motherboard.
In addition, unplug any un-necessary USB devices.
If issues persist please seek assistance at https://support.logi.com/