LevelStreaming causing AI error

I have started to learn to UE4 about 2-3months ago and it’s been quite a blast.
However, I recently stumbled upon the Level Streaming method. I feel like I’ve grasped on what it is, why it is used and how. I had some test runs on it yesterday and ended up with some error I couldn’t figure out.

So the idea is, I’m making a 3d TopDown RPG, with all the typical stuff. The main selling point being some radical decisionmaking on the story. But to the issue in hand:
I have a TestMap, where I’ve tested the features to be implemented. I have a simple non-animated EnemyPawn, with simple-ish Ai, that moves randomly every 1-5s. But if PlayerCharacter gets within its AGRO-sphere, it would chase the character. So far it works all fine with no errors.
But as soon as I start playing with Levels (Persistent level, with MainMenuScreen and TestMap under it), something funky happens. Game starts normally in the Main Menu, I click New Game, good so far. It loads TestMap, but as soon as I exit from this screen, I get some error messages:
Which link me into this:

First 2 errors link me to the upper “Set Value as Bool”, and the 3rd error is the lower one.
Below is the AI Behavior Tree:

Just curious as it doesn’t give errors at all when in the TestMap only.

Also bonus question:
If my project is aiming to be similar in gameplay as Final Fantasy 4 (3D version), is Level Streaming a thing to go for, or would it be better to go with just Level transition triggers?