SD-WAN strategy is Lowest Cost (SLA) as indicated by the "Mode(sla)" flag. Cost SLA uses SLA target, cost, and priority (i.e., interface preference - or order of config unless manually overridden by admin config) as the criteria -- in that order. Both members meet the target, both have 0 cost, and therefore member 3 (T_INET_0) wins the "priority" tiebreaker. So if there is a valid route to the destination through member 3, it will win. The fact that it does not has nothing to do with the configured static route/member priority, which according to SG page 197 "is used as a tiebreaker for ECMP routes when matching implicit SD-WAN rule."