Not all bones animating

I’ve imported a walk cycle from blender, but only the spine section of the armature seems to be animated in Unity. As a result, the character only rotates back and forth slightly, but the limbs don’t move.

Any ideas on how to solve this?

Most likely because in Blender you got IK in your Rig. FBX doesn’t understand IK, and so you can’t directly export IK to unity.
You will have to plot your animation in Blender and possibly deactivate IK controllers before exporting.