From Kernel/System/Ticket.pm:
# do not execute acls it userid 1 is used
return if $Param{UserID} && $Param{UserID} == 1;
..
# check acl config
my %Acls;
if ( $Self->{ConfigObject}->Get('TicketAcl') ) {
%Acls = %{ $Self->{ConfigObject}->Get('TicketAcl') };
}
Later, you can see that if the Debug level is > 2, it will tell you what Acl is matched.
To do this, in Config.pm write
$Self->{Debug} = 3;
It might give you too much information, but you should also be able to see how to add your own Log where you wish to debug.