Can't save new form when Wordpress is running from a subdirectory

[rickgladwin]

Description: Creating a new form and hitting save gives the "Custom Contact Forms is experiencing issues." error. The plugin was working when the site was under test, running from a subdirectory. After making the site live by updating the Site Address, htaccess, and index files, Custom Contact Forms no longer works.

To reproduce:

• Install Wordpress in a subdirectory on a server where Wordpress is already installed in the root directory (remaining steps performed in this new site, in the subdirectory)
• Set up theme and pages in the subdirectory
• install Custom Contact Forms plugin and create form, include the form on a page
• go through the steps for making the subdirectory site site live site ( https://codex.wordpress.org/Moving_WordPress#Moving_Directories_On_Your_Existing_Server )

Expected:

• Contact form can still be submitted
• New contact form can be created
• Existing contact form can be edited

Actual:

• Contact form behaves normally in the user-facing views, but no messages are sent (no console errors, no errors logged on server)
• Trying to save a newly created contact form results in the "Custom Contact Forms is experiencing issues." error and this error in the console: load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.4.2:5 POST http://hammercityrollergirls.ca/wp-json/ccf/v1/forms 403 (Forbidden)
• I can view the existing contact form in the list, but no "Manage Form" button appears (can't edit)

Tried:

• re-saving permalinks --> no effect
• deactivating all other plugins, installing 2016 theme --> no effect
• deactivating and reactivating Custom Contact Forms plugin --> no effect
• uninstalling and reinstalling Custom Contact Forms plugin --> no effect (my existing form is still present, and still doesn't work)
• uninstalling Custom Contact Forms, deleting all records in the database with field data matching 'ccf_%', reinstalling Custom Contact Forms --> existing contact form is gone, can't save newly created form

Notes: The critical change seems to be running Wordpress from a subdirectory. This is not an edge case though - this directory setup is very common, and this is a very common way of replacing an existing site with a new Wordpress site.

[tlovett1]

What is your site url and home url?

[rickgladwin]

Site URL: http://hammercityrollergirls.ca Wordpress URL: http://hammercityrollergirls.ca/hcrd-wp

/public_html/hcrd-wp is a real directory, in which Wordpress is installed