I’m Having exactly the same problem, im doing a level streaming with nav mesh invokers, using spawn triggers to spawn my AI Actors.
If i set my nav mesh to 10k x 10k x 10k (x || y || z) Nothing generates, if i make my nav mesh 10k x 10k x 800 it generates perfectly, so i thought maybe all i need is to take away my Y and add to my Z (since im doing a side scroller) but it wont work, basically any nav mesh higher than 800 wont generate.
Anyone knows about this or can help with it?