Defined types in schema.Schema not being honored?

While developing a provider I’ve come across situations where the defined type of a schema item is not being honored.

Introduction & Explanation

				"enabled": {
					Type:     schema.TypeBool,
					Default:  true,
					Optional: true,
				},
				"level": {
					Type:        schema.TypeInt,
					Optional:    true,
					Default:     1,
					Description: "The level of compression used for gzip",
				},
    delivery = {
        compression = {
            enabled = true
            level = 2
        }
    }
mapContainingCompression := d.Get("delivery").(map[string]interface{})["compression"].(map[string]interface{})
test := mapContainingCompression["enabled"].(bool)
test2 := mapContainingCompression["level"].(int)
panic: interface conversion: interface {} is string, not bool

&

panic: interface conversion: interface {} is string, not int

This same process is working fine with other schema fields, however. Dumping the data via a log shows they are what I would expect

		map[enabled:true level:2]

Question

What can be causing this? Why would they not be coming through properly