logging router activity

I would like to log router activity (for example, when WAN1 goes down and traffic is redirected to WAN2). I believe I have everything set up correctly, but my router logs are empty. It seems simple enough: just check the "router activity" box in Log Settings, right? 

Here's the relevant portion of the config:

config log eventfilter
    set event enable
    set system enable
    set vpn disable
    set user disable
    set router enable
    set wireless-activity disable
    set wan-opt disable
    set endpoint disable
    set ha disable
end