How to tell why AssetBundle won't load from file?

Hi,

I'm trying to load an asset bundle I've made. It loads fine in my unity project but on an actual build it won't load. I've checked and double checked the path (inc. with a check with File.Exists()). AssetBundle.LoadFromFile() just returns null and doesn't tell me why it won't actually load.

Any help working out what's actually wrong with my bundle would be appreciated

 

I am getting some kind of issue still not able to load prefab from the bundle.
https://github.com/TheIntellify-Hardik/SBP-Exmple.git

here is the sample code.