Hi @jrrsantacruz,
I’d say it must be a cache issue. See
1) The file that first declares that function doesn’t exist anymore since version 4.6.0 —which you must be running because the mentioned function is also present on the deprecated functions file.
2) It’s happening on any environment you test
So, are you sure you have cleared all the caches in your installation? Some hosting providers have enabled additional caching mechanisms —other than WP plugins, I mean— that might be loading old files.
Another option would be that the plugin update process failed somehow. Adding new files but not removing the ones that needed deletion. This would be really weird, however.
Anyway, you can always remove the plugin and install it again. Plugin settings will be kept —as long as you didn’t change default plugin configuration regarding data retention upon deletion. But if it is a cache issue, I’m not that sure this will make any difference.
If none of this helps, please provide a list of contents for the plugin folder. You can paste it here or open a support ticket with us here.