To debug check nft rules
sudo nft list ruleset
And figure out what is going here vyatta-wanloadbalance/src/lbdecision.cc at current · vyos/vyatta-wanloadbalance · GitHub
There are no easy solutions for debugging, as WLB is outdated ⚓ T4443 Wan Load Balancing Multiple Regressions
The proposed replacement “protocols failover route”