Player Start "BAD size" icon

Hey,
I exported an fbx file from Blender into Unreal Engine 4 and i have same problem with controller. It says “player start bad size” and gets stuck if i simulate a play. I’ve tryed moving it away from closest objects but it accures that my interior model is being seen as a full block (i can walk on it if the cotroller starts above). I’ve seen an explenation on some forum that i have to defragmentate the model but i don’t really know how since it is defragmentated in Blender . What said #jaredcfw- “it automatically created a collision mesh of sorts” sounds like thats it but i don’t know what does it mean. If you could tell me the way how to resolve or show me a tut i would be very gratefull. Please note that im new in the subject so if you could explain it like i was retarded it would be also cool.
Greets,