Hi @pickme,
I’m not entirely sure how mod_security handles catching custom code. If you’re able to whitelist the wp-content/plugins/code-snippets directory or wp-admin/admin.php (depending on whether mod_security works on a source or URL basis), then it should prevent it from catching snippet code.
Hi @pickme,
Looks like Victor has found a solution to this in another thread. Here’s the link; hopefully it will work for you as well: https://wordpress.org/support/topic/file-not-found-when-saving-snippets/