Multi WAN: unable to ping both modems

[maxxer]

Hi.
I've configured 20.1.7 with MultiWAN. It seems to work fine but I cannot figure out why I'm unable to ping both modems at the same time, only one of the two is available.
I checked the config it looks as per docs: the two WANs have two private 172.x networks, I configured the two gateways and gateway groups. The default firewall LAN rule is set in fallback mode, that is traffic going through one gw and using the second as failover. Ping from the firewall works for both modems, but from LAN only one of the two is responding. Ping from LAN to the gw monitoring IP works for both, but traceroute shows the same path for all! I.e. right now despite both gw being online LAN traffic is going through the secondary one!

Any hint on where to have a look? Thanks

[maxxer]

attaching gw status