Site won't display messages I'm desperate.
I have a site with 2 databases, staging and production, and in staging messages set with drupal_set_messages() appear, but in production they don't.
The codebase is the same. I tried switching database settings on the same codebase and the behavior will change depending on the database.
I have inherited the site so I'm not 100% familiar with its configuration.

My question is: is there anything on a database level that can block messages from showing? They appear in the admin area, but not in the rest of the website...
Configuration &gt; Development &gt; Logging and errors has some settings on whether to display drupal messages or not. You might check to make sure that it is properly configured for your use case. 

Path to config page: /admin/config/development/logging