Palo Alto Firewall with GRE multiple /32 ips from same subnet

Has anyone tried adding more than 1 /32 ip from the same subnet on a Palo Firewall, added in the GRE tunnels using tunnel interfaces, and setup ECMP accross the multiple tunnels to Zscaler Zen nodes?

from what i tried its not possible to add more than one tunnel to the policy routing in the way i am trying.