IP Filter Session Close simply means that a session that was allowed through the firewall using a Packet Filter (IP Filter) was closed either by timing out, or some device sending a fin or reset.
Proxy Traffic End is the same thing but involves traffic through the proxy.
Accordingly, my system shows Proxy Traffic End. Does it mean that the session has been blocked.
I would expect a session being blocked by the firewall to result in an "ACL Deny" (if the traffic has hit a rule which explicitly denies access) or maybe something like a "Protocol Violation".
Based on what Matt is saying these "IP Session Close" or "Proxy Traffic End" records are the firewall reacting to a status change on the part of the original client or server - either one party is timing out or it is issuing a 'fin' or 'reset' packet.
Yes Phil is correct. Proxy Traffic end means the connection was allowed, then closed out for some reason (timing out or fin or reset).