Hey Dedricus,
There are generally 2 things that can cause you to not see anything:
1. I suspect this might be the culprit: You need to generate AI/Vision/Material information. The
AI Grid Panel is used for generating information concerning AI (where characters can walk), Materials (sounds of the painted terrain layers) and Vision (where characters can see or not). If vision information in particular is not available, you won't see anything. And if AI information is not generated, you won't be able to move to anywhere where you can see. Place a Start Trigger, or an AI Seeder Trigger from the
Root template panel anywhere in your level and press the "Full Generate" button in the
AI Grid Panel.
2. Do you have a player character? In-engine you should get a dummy. If that's not the case, you can place a character from the
Root template panel and set the "Player" value to true. You'll know you have a player in game mode, if you have his portrait on the left side. If so, just double click on it to be sure it is selected and you see its skill bar.
Hopefully it's one of those two

Else we'll look further of course.