Hi,
Thank you for the details!
The issue is caused by a 3rd party plugin (most likely), as I am seeing a function wrapped around the localized script: https://i.imgur.com/0UNimPx.png
Wordpress does not do that by default, so something else is probably placing a function scrope around the localized string – this causes the variable to be undefined. I suspect maybe a cache plugin or something similar. I understand their intention, it is to probably increase performance, but the variables declared via wp_localize_script will be unusable, due to the function scope. I strongly recommend fixing this, whichever plugin is doing that to the localized scripts – as by default developers tend to use that within the window variable scope.
