This is the initial release of Migrate Process URL!
A custom migration may only have a URL to import into a field. If using Drupal core's link field, you have to assign the value directly to the uri column:
uri
Fixed:
See the full release notes at: http://docs.aegirproject.org/en/3.x/release-notes/3.17/
Fixes security issue https://www.drupal.org/sa-contrib-2019-003