I've been importing photos with the picture-urls::(original)
field for years but since 2018/2/26 about half of profiles have not been returning this field and since 2018/3/1 none of them have been returning it. The picture-url
field is not a usable substitute since the photos are too small.
The field is still documented as part of the basic profile. Several others are having this problem too:
Linked in Omniauth photo_urls or picture-urls::(original) not being returned
LinkedIn not picking up og:image from wordpress