This is due to a URL change made within the Twitter API. That much is fixable but, combined with the new usage rates, I’ve found it almost impossible to get any usable data from.
Artiss Twitter Data is dependant on the original, easy to access, API that Twitter provided. Unfortunately, they are now moving everyone towards an authorised, more complex system – far too complex for this, simple plugin.
I am, therefore, regrettably withdrawing this plugin from use. I will leave it in the repository for a short time before asking WordPress to remove it entirely.
I apologise for any inconvenience that this causes.
If anybody would like to take over ownership of the plugin then please let me know.