Not possible to select language on login screen

I'm trying to find out how to enable the language drop down selector for users who are NOT signed in.  We do not have 'require sign in' checked for our KC. We have visibility for some articles set to 'everyone.'  However, when viewing those pages, the language drop down is not enabled.  Our company recently merged with a company whose ZD KC is available to users not signed in, and they can access the language selector drop down, so I know this is possible. Any idea how I can replicate this behavior?

Hi Lil! We addressed this a bit in your ticket regarding this, and with our investigation together it seems it was related to custom code in the theme itself.
Please follow up on our ticket if your team continues to run into issues with this, especially if it persists in the default Copenhagen theme - while we can't help with custom code directly, we will be happy to help you ensure the underlying functionality at the very least!

Thanks Jon. Unfortunately, I was not with the company when the custom code was implemented and there is no record of changes made, or why the changes were made.  I realize you cannot help with custom code, but do you have a list of changes to code that might have a negative downstream impact?  If not, something like a "tips and best practices when customizing your theme" article would be very useful in the future.