Since it is a custom PHP codes question, I need to check it in your website, and will feedback if there is anything found
Luo,
When I removed the default value for the custom field, the above function worked perfectly.
The only issue I have now is changing the value of the custom field on existing posts that have the default value saved in the database. I tried to use the edit form for the CPT in hopes that the existing function would update the value, but unfortunately it didn't change anything. I've also tried editing on the backend by deleting the default value and then updating the post, but again the default value still shows.
Please create new thread for the new question:
The only issue I have now is changing the value of the custom field on existing posts that have the default value saved in the database
If you need to use CRED form to update the custom field in front-end, you can simply create a CRED form for editing the post, create custom PHP codes, use action hook "cred_save_data" to update the custom field "wpcf-full-record-date" value.
https://toolset.com/documentation/programmer-reference/cred-api/#csd
If you need to update the custom field "wpcf-full-record-date" value in admin side, you can try wordpress action hook "save_post":
https://codex.wordpress.org/Plugin_API/Action_Reference/save_post
Thank you Luo. I am working on those suggestions now.
OK, please update this thread if you need more assistance. thanks