When going into the mouse settings, configuring an extra button (top right corner) and adding a binding, the mouse input is not recognized. The mouse input is recognized in general. By default it emits a back/forward input (at least for my mouse). Even while binding a new mouse button it gets recognized and I get redirected to the previous screen. I have tested this on two different setups (100% different hardware) with different hardware (both using the same fedora install).
I can confirm this on git-master and 6.4.5 with a Logitech G502 Lightspeed mouse The UI does not react to any mouse button that isn't the left or right click buttons.
*** This bug has been marked as a duplicate of bug 506342 ***