WANfailover - doesn't fail back when Cold-Standby?

[Nexus6]

Hi all.. WANfailover is great tool..thanks a lot for all your efforts... I've installed it a couple of days ago to trying to fix a scenario with my router Asus RT-AX88U, but I haven't been able to fix it, even with wan-failover... it is like that: I have the main internet access on WAN0 and on Port 3 (WAN1) a backup 5g solution (modem). The scenario is as follows: I disconnect WAN0 (unplug the ethernet cable). It fails as planned over to WAN1. I then restart the router (as I now and then do...and that's probably the tricky part).. router comes back up and connects again on WAN1 (because the ethernet on WAN0 is still disconnected) . I plugin the ethernet cable to WAN0... expecting it to failback when connected... however, that is then never happening. It will remain on WAN1, no matter how long I wait. The status on the router is "Cold-Standby" on the Primary WAN, connected to the Secondary WAN. It will not fail back, I even tried a "switchwan" in the console. it doesn't do so... in wan-failover status WAN0 is marked as Status: stopped (see picture)... the only way to fail it back is to restart wan-failover... Any ideas?