When I delete part of the landscape UE4 crashes

LoginId:b99edc9641f99dbface4709c16d6c369
EpicAccountId:053ebd9370634e42999514a0cb374e0b

You do not have any debugging symbols required to display the callstack for this crash.

https://vk.com/video171164625_456239065

engine versions 19.1

I have the same problem with v19.1.