Artifacts from the previous Launch On are being cleaned up, which are necessary for improved iteration time.
Tested from a Windows PC
RESULT: There is a full recompile which takes a long time (The 2nd Launch On took 23 minutes for me)
EXPECTED: There should not be a recompile, and iteration time should be fast
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-60264 in the post.