Custom field content disappearing after update on custom post types

Hello!

I’ve created a custom post type for a site I’m building, and added a pile of custom fields to enhance these posts. Anytime my client updates one of these posts (and this will continue to happen on a regular basis…), all of the custom field content disappears.

I’ve tried multiple solutions found both in the forum, and through Google, and none of them are working to rectify this.

My code can be found here: https://pastebin.com/E3kz1exu

Is there something else I can add to make these fields stay populated?

TIA!