No session rematch just compares all your existing sessions against the new policies you are committing. If there is a match they stay and if they are now being denied they are closed.
To figure out why the sessions are blocked you will need to first verify that the session is not created using
show security session flow
As noted above. If the session does exist then the issue will be with return path routing or the policies on the other J-series firewall.
If there is no session, use the trace options above to get the reason the session is being denied.