Red Lines means
narrow Paths - which means Bot Paths more exactly. The fact is these paths need to be Two Way and not One Way.
With other words Red Lines are not wrong if they are connected normally.
By any matter you can use
PathsDebug builder tool posted in forum by Buggie and do some check if Flags are having links each-other... later we can talk about AlternatePaths.
To not forget what is NOT explained in tutorials is that overcrowding nodes will generate useless Paths never used in game and errors causing loops. Polge from Epic is the coder of these devs and then, there is no other tutorial more relevant than original tutorial explained by the man from factory, which still has some information missing. It's about several tricks, community assets and more others. Red Lines story when it comes to a Bot map is not really relevant - that's for monsters in SP Coop MH maps or whatever maps aiming more or less stock creatures.
What a mapper needs to know is that a PathNode is like a station where a train stops and it will move to next station until it reaches at destination. It's why Plain Nodes should not be in air because trains are not levitating - in the terms of logic placement - aerial nodes are poorly connected into navigation network generating gaps/break points. There are situations where special combos might be used for causing pawn to jump or to do some stunt but that's another story.
Note: UT patch 469b comes with an Editor having another deal toward paths graphical representation using colors and arrows. Also UT 436 and XC_Engine v24 with XC_EditorAdds can show something similar, helping human mapper to figure missing paths. Red Lines and Blue Lines are not showing too much, for me they are irrelevant in the way how are drawn.
