Thanks for yuor reply.
From the errors you reported it is clear that some of the frontend scripts are not loaded.
The frontend script for the address validator is not loaded, and the JQuery qrcode script seems to be missing too. This would explain your issues. Some thoughts that come to mind:
Could it be some problem with a CDN you use?
Or a misconfiguration of your web server? Try to determine why the assets would not load.
Is this a new installation? Did you change something on your server recently? Does the plugin work when you disable other plugins?