Prefabs not found

Hello guys,

I am running to an issue since a while where prefabs and models are not loaded properly by "FindObjectsOfTypeAll" if at all whether in Editor or Build to instantiate them into the scene. It drives me nuts. In Editor the prefabs can be found after clicking on them in Project view. But when I Build my game the Standalone doesn't find the prefabs at all. It is especially wierd because since I am using the same methods as I did back two years ago and it worked.

I tried Resources.Load("..."), AssetBundles etc. A list of these prefabs works in Editor, but not in Build... I then thought it could be an issue due to my hardware: Unity was on my SSD and my project on the HDD, but even putting both on the same drive did not solve this issue. My models are in .blend files, but putting them into seperate meshes doesn't work either.

However if I place said Object into the scene and then try to instantiate them it works fine - which is not an ideal solution. Do you guys know any solution?

PS: I tried Unity 2018.2.12f1 and predecessor version.