When "Use Background Level Streaming" is disabled, the Editor gets stuck loading in PIE when you press Play. This is a regression from 4.19.2 (CL-4033788).
This issue was reported and tested in 4.20.2 (CL-4302132). This was reproduced in Main 4.21 (CL-4313833)
Result: The Editor gets stuck trying to load PIE
Expected: PIE loads up and you can move around
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-63320 in the post.