Unable to update ACF fields on Media items

We have tried every which way, but we cant get this to work, its always a 500 error. Here's our current code. 

`curl -X POST -v \
-H "Authorization: Bearer ${TOKEN}" \
-H "Content-Type: application/json" \
-d '{
	"acf": {
		"test_media_acf": "A35BC0980D"
	}
}' \
"https://x.x.x.x/wp-json/acf/v3/media/16"`

Are we doing something wrong? Any suggestions we can try?