After upgrading to 4.21 the AI stopped working correctly in built games (shipping/development configs, they both have the same behavior). It works fine when playing in editor.
I know there are some issues with AI navmesh generation that happens in this version (navmesh doesn’t generate/loads fully after loading a map which we observed here as well) but this one is a bit different because calls to TestPathSync seem to always return false (while it worked in 4.19 and it still works if played in editor).
Not sure how to approach this (to overcome it we could rewrite the code to not use these calls but at the same time while it works in editor fine we believe it is a build problem which might be related to the navmesh generation thing and we prefer to get feedback from unreal. It is s big project and very far in development and we would like to keep the logic the way it is.
Let me know if anyone has any suggestion!
I believe the change causing your issue is actually from 4.20, not from 4.21. You might want to look at the 4.20 notes