When importing layer information to a landscape the engine will freeze and consume all available memory. Unable to test in 4.19 due to provided project being made in 4.20. I have attached a log from the project where it seems to be building the same textures in a loop.
Found in 4.20 CL# 4302132 and 4.21 CL# 4370874
The editor will freeze and consume all available memory over time.
The layer would be imported
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-64175 in the post.