Hi I think its because of pbr your telling the router when traffic hits from either subnet to there gateway LAN interface redirect them to this ip address next so the routers not processing inter vlan traffic as its being redirected first , why don't you just use static routes and direct each subnet out each ISP link
example
ip route 192.168.0.0 255.255.255.0 217.x.x.x
ip route 10.0.0.0 255.255.255.0 134.x.x.x
You could also have 2 default routes pointing to each external ip too using cef asa crude form of load balancing