If you get blacklisted/locked out despite of having your IP whitelisted with Shield, please ensure the IP address source under Dashboard => Plugin Defaults is correct.
You can use the Welcome Wizard to set that up: Dashboard => Wizards => Getting Started Setup Wizard.
If this doesn't help, please use Audit Trail Viewer to review your site activities:
It will tell you exactly what's going on, what's being blocked....so you could get the problem resolved.
Note: In case you get locked out of your site, follow the guide outlined in the article here.