Custom field post type not showing in post editor

Hello, I cannot figure out why a custom field will not show up in the post editor. This particular theme uses the Types plugin to create custom post types.

There are 3 radio buttons to select a link type.

If the Internal radio button is selected, then the Internal input field appears:
https://db.tt/X49Ml9Kr

If the External radio button is selected, then the External input field appears:
https://db.tt/C7imcSZM

If the File radio button is selected, no input field appears:
https://db.tt/zghOW5qO

Here is a screenshot of the link type custom fields:
https://db.tt/kyv5JhrE

Here is the file field set up:
https://db.tt/oAs8Ff2Y

I don’t know what I’m missing.

Thank you!