It depends on how the packets get routed based on routing or PBR.
To get an idea why the packet is routed back to the outside interface you can also have a look at the route lookup phase in the packet tracer.
I am guessing the traffic is being dropped at the acl phase because you do not have same-security-traffic permit intra-interface configured.
To get more info with the packet tracer you can run it from cli and add detailed keyword.
HTH
Bogdan