hidden connections: where are they ?

Hi all.
I mangle all traffic in forward chain as OTHER_CONN, then I mark all packets as OTHER_PACK.
After this I have some rules to mark traffic in the same forward chain: VOIP, HTTP, P2P.

When I go in ip>firewall>connections, at the bottom of the window I can see:
“2057 items out of 28994 | Max Entries: 524288”

My problem is:
sometimes I want to check if a known connection is correctly mangled and the only place where I can read the connection mark is in ip>firewall>connections.
But I can print the searched connection (I know the source ip address and port) only if this connection is in the 2057 connections showed by winbox.
Why this ?

thanks