you could use the built in procedural generator
https://gfycat.com/acrobaticadorablebluebreastedkookaburra
I have noticed that happen occasionally and have it on my list to fix. Are you running Linux?
Ahh found the bug. looks like if you dont manually set your sky, it doesn't register it and will load with the default sky, thanks for bringing it to my attention, will fix for the next update
Is there an API for testing our own procedural generators? I was wondering whether I could use it as a testbed for my students.