I was following this GAEA tutorial: Create Massive World in 30 min - Unreal Engine 5.1 and Gaea - YouTube
when the instructor said to turn off exponential height fog for it work… is there anyway to have this landscape while having fog?
Hi there 
To be honest, I didn’t see that video, but I’m pretty sure that enabling fog won’t make the landscape disappear. Did you check all the angles & the landscape has not gone under the fog?
Try to play the game at a proper player start location (above the landscape), or reply with a screenshot so that I can help you more precisely.
exact same problem here…