Accessed none trying to get blackboard

Whenever an enemy is spawned, it will always have this error:
Blueprint Runtime Error: “Accessed None trying to read property CallFunc_GetBlackboard_ReturnValue_1”.

This error is from the sight AI Perception. This error wouldn’t bother me too much, except it occasionally seems to cause the AI to not be able to see me at all, unless I damage them and “reset” the perception. I have the ‘Run Behavior Tree’ in my startup and even have a delay to make sure that everything can initialize. Here’s some images of the failing node and my startup:

Any ideas would help. Thank you in advance.