Some mouse button events are not sent to remote machines

[trustin]

I have a 'Logitech MX Anywhere 2' mouse connected to a local Linux machine. When I send my cursor to a remote machine, the usual mouse events like movement, left/right/middle clicks and wheels work as expected. However, the fourth and fifth button which are used as 'backward' and 'forward' do not work in the remote machine. Nothing happens simply when I click the buttons.

I believe these buttons all generate mouse events at Xorg level given these buttons work just fine locally. Could you please make sure Synergy sends all mouse button events to remote machines? The following is the Xev output when I press them:

ButtonPress event, serial 48, synthetic NO, window 0x4200001,
    root 0xdc, subw 0x0, time 36766585, (111,75), root:(112,878),
    state 0x0, button 8, same_screen YES

ButtonRelease event, serial 48, synthetic NO, window 0x4200001,
    root 0xdc, subw 0x0, time 36766655, (111,75), root:(112,878),
    state 0x0, button 8, same_screen YES

ButtonPress event, serial 48, synthetic NO, window 0x4200001,
    root 0xdc, subw 0x0, time 36776758, (111,75), root:(112,878),
    state 0x0, button 9, same_screen YES

ButtonRelease event, serial 48, synthetic NO, window 0x4200001,
    root 0xdc, subw 0x0, time 36776894, (111,75), root:(112,878),
    state 0x0, button 9, same_screen YES

(Synergy 2.0.4)