custom metaboxes for custom post types

This is a site under development and the issue is in the edit post area so it is not possible to give you a meaningful link to the site.

I’m trying to add custom meta boxes to a custom post type and I have success with

Here’s my code: https://pastebin.com/2bE6akPb

I’ve been following a very useful tutorial that has helped me get this far. Here is the link to that source:
https://wptheming.com/2010/08/custom-metabox-for-post-type/

The data is being stored in the database meta for the custom post type, and I can display it on the single output, but it is not displaying in the text box area on the edit post screen.

Could one of you who knows more about this than me so kind as to have a look and let me know what I’m missing?