This link looks broken,
I’m running into the same issue now when I try and package my game too.
D/UE4: [2017.08.27-13.51.34:040][ 0]Assertion failed: Assertion failed: RecursionNotAllowed.Increment() == 1 [File:D:\Build++UE4+Release-4.17+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading.cpp] [Line: 4235]