If you mean the ZOC borders: Far as I know this is not fixed. But if you do the following you will almost never see it: First never load a game unless you just started FELH and havent done anything yet. Second dont use Ctrl-N. I think the bug still happens (very rarely) inside the game though. If it does you can fix it by save + quit + restart/load.

About 'neutrals dont attack'. I have seen (old official Stardock) forum post/s implying that this is intentional for higher world difficulties. Otherwise wandering monsters supposedly dont target human players over AI players. I dont know if this is true. However I do know that for lower world difficuly settings AI players are targeted by wandering monsters. So your "dont attack" implication is wrong if you use lower world difficulty settings. Also note that there are 'rules' for wandering monster attack odds which you may be unaware of - for example they usually prefer units over cities.

ZOC-Disappearing...I know that it is still not fixed...therefore this Thread...i happen random after some time or every time you reload your game after the "Start/continue"-load.

Neutral's don't attack...I play on challenging on all settings and after the change to LH the Dev. stated that AI plays now the game you play, starting from Expert-KI they get Buffs for HP, more Ress and buffs to other Stats, expect for factions with the right feat they should be attacked like the player, the Worlddifficulty should not affect the KI-behaviour.

During my last game(finished it yesterday) with a custom Ironeer-Faction i observed 70% of the game via the scry spell, during the hole time( nearly 500 Seasons, on a huge map with 5 remaining AI-factions) game it happend once! that one of the AI-engi-armies was attacked.
Otherwise their engis, caravans, scouts travel savely, they even settle directly next to dangerous threads, none of their outposts or ress-locations was attacked. They even cleared a wildarea that only had the "free the area of all Monsters", they settled/builded outposts directly at the border, their ZOC raised and Mobs moved on after some seasons all Monsters had left the Wild land it the Quests disappeared...at the opposite site of the "no-longer-wildland" you had roaming armies of shrilllord and dragons. Before moving on this armies just stand around, often directly next to settlement or a outpost.

A sidenote of my observation....4 of the 5 Ki-faction should be broken because the had far to many citys without choosing unrest-reducing improvments, instaed they most the time choosed improvemts that rise the unrest further. All their citys showed a unrest over 90%...still, they produced like hell, pumping out engi after engi and army after army....


Edit: I Play FE:LH some years now, a game or two then i get angry with some of the more annoying bugs/glitches or plain stupid stuff that has not been fixed even while beeing known since EA of FE vanilla. I know that the KI used to kill themselves with to fast expansion..that was really bad...but just deactivating unrest/neutral-attacks it's no solution..it's just plain stupid and killing immersion because dealing with the Neutrals&Wildlands is such a important part of the game. I win 95% of my games on challenging and the ones i loose are most the time some crazy RPGidea-custom factions. So understand it's not about difficulty. As i wrote at my first post..it's about immersion and Atmospere.