I think this is some quirk with Unity and Blender. I only have a single object so when importing in to blender it’s setting the X rotation as -90. At 3:36 in the video when you go into the individual meshes each one has it’s X axis rotation set as -90 which is the same thing I’m experiencing. I’ve just done a test and added an additional object in to my file and the parent container x rotation is 0 and the child meshes are -90.
So it looks like having a empty parent object will do the trick. Thank you for your help!