Unfortunately (or fortunately 
) I couldn’t recreate the problem. what happened for me again today was that the refresh button on the Failover page (screenshot below) doesn’t work and refreshing the whole page updated the Failover is actually acting the way it should.
Also, the Network → WAN page doesn’t help much. When something happens and I don’t know which WAN is being used as the main one, I need to go to the failover page, especially when there are multiple WANs (more than 2) and more than one of them are alive, and RUT should select the one with higher priority.
In the Failover page, i have the possibility to see that the lower priorities are in the “Standby” state when higher priority is “Online”.