NPC patrols getting into my fully walled base

[Kaelum]

Alright, here it goes. I've got a problem with my base, occasionally I'll find inquisitors or other hostile npcs that have somehow managed to get in through the back. Since my main squad is away, this either means heavy micro or letting my noncombatants get the stuffing beat out of them. My main base is up on a plateau in the fog, and I've checked my entire perimeter several times. There is one place at the back (extra heavily walled now) that raids seem to path to. When they arrive they mostly just stand around staring at it, but the fact that they consider it a viable path may be important. Can't seem to upload my save as it's too large, may try commenting on my own post to circumvent this. Pictures attached.

Navmesh and fix stuff has been tried, wall directions have been checked.

[Gabthelazy]

Can't you archive the save folder?
The glitch has been happening to a lot of us. Hope it gets fixed soon.

[Kaelum]

Even archived with the best compression I can get, I can only get it down to 32MB. I guess I'll just upload it in a multi part RAR.

[Kaelum]

Part 4-6 attached

[Kaelum]

Last part, sorry for the spam