I use Emsisoft free version of Online Armor, and I try not to set applications to "trusted" unless I absolutely have to.

Usually OA will ask me to approve everything the app tries to do, but after the initial "This application wants to run" question, Overlord would just become unresponsive and OA didn't ask any further questions, which is highly unusual. I suspected my firewall was interfering so I started messing around with the setting and it turns out my suspicions were correct.

Enabling "Use DNS API" and "Enumerate files" in the advanced options for Overlord.exe fixed it. I have to allow those for pretty much every game I want to run anyway, and that way I don't have to completely trust the executable. It's the first time I have to go set them manually instead of doing it through OA's prompts however.

Just wanted to share my experience in case anyone runs into the same situation.