I think I found the problem...could it be due to the animator controller and avatar my arms use? My first person arms use the "Demo" animator controller, not "FirstPersonArmsDemo". The reason I have it this way was the FPS Mesh Tool (which I bought and use) Integration video from Opsive advises using the "Demo" animator controller when first setting up the arms. However, using the same animator controller and avatar as "Nolan's" first person arms results in a T-pose. No animations whatsoever.
For reference, here is the prefab settings on the arms from FPS Mesh Tool.