Just got this error almost as soon as I opened the game. Cracked open a save, realized I accidentally hit the wrong one, quit, hit the right one this time, got the error before the loading screen even showed up.
Assertion failed: InPos >= 0 && InPos <= TotalSizeOrMaxInt64IfNotReady() [File:D:/Build/++UE4/Sync/Engine/Source/Runtime/CoreUObject/Private/Serialization/AsyncLoading.cpp] [Line: 7451]
Bad position in FAsyncArchive::Seek. Filename:../../../GrowthRPG/Content/Maps/Final/FinalOverworld.uexp InPos:665218881, Size:299074372
0x00007ffbee36fe4c KERNELBASE.dll!UnknownFunction []
0x00007ff69999c416 GrowthRPG.exe!UnknownFunction []
0x00007ff6999a02e8 GrowthRPG.exe!UnknownFunction []
0x00007ff6996f6f5d GrowthRPG.exe!UnknownFunction []
0x00007ff699659d45 GrowthRPG.exe!UnknownFunction []
0x00007ff69965b4b0 GrowthRPG.exe!UnknownFunction []
0x00007ff69ef0e66d GrowthRPG.exe!UnknownFunction []
0x00007ff699adbce9 GrowthRPG.exe!UnknownFunction []
0x00007ff699b3ac6a GrowthRPG.exe!UnknownFunction []
0x00007ff699b38b38 GrowthRPG.exe!UnknownFunction []
0x00007ff699d6c592 GrowthRPG.exe!UnknownFunction []
0x00007ff699d6c7c5 GrowthRPG.exe!UnknownFunction []
0x00007ff699b3aac9 GrowthRPG.exe!UnknownFunction []
0x00007ff699b38b38 GrowthRPG.exe!UnknownFunction []
0x00007ff699d6c592 GrowthRPG.exe!UnknownFunction []
0x00007ff699d2ca0d GrowthRPG.exe!UnknownFunction []
0x00007ff699d6c7c5 GrowthRPG.exe!UnknownFunction []
0x00007ff699b3aac9 GrowthRPG.exe!UnknownFunction []
0x00007ff699cc6ffe GrowthRPG.exe!UnknownFunction []
0x00007ff699cc4a03 GrowthRPG.exe!UnknownFunction []
0x00007ff699cc4870 GrowthRPG.exe!UnknownFunction []
0x00007ff69d3845af GrowthRPG.exe!UnknownFunction []
0x00007ff699a9e0e4 GrowthRPG.exe!UnknownFunction []
0x00007ff699ac5f30 GrowthRPG.exe!UnknownFunction []
0x00007ff699a78e38 GrowthRPG.exe!UnknownFunction []
0x00007ff699ac302b GrowthRPG.exe!UnknownFunction []
0x00007ff699ae5b9b GrowthRPG.exe!UnknownFunction []
0x00007ff699ae3482 GrowthRPG.exe!UnknownFunction []
0x00007ff699aaebcc GrowthRPG.exe!UnknownFunction []
0x00007ff699b0f9cf GrowthRPG.exe!UnknownFunction []
0x00007ff699da1e8c GrowthRPG.exe!UnknownFunction []
0x00007ff699da17e0 GrowthRPG.exe!UnknownFunction []
0x00007ff69da6c44e GrowthRPG.exe!UnknownFunction []
0x00007ff69da1e232 GrowthRPG.exe!UnknownFunction []
0x00007ff69da8c3f8 GrowthRPG.exe!UnknownFunction []
0x00007ff69d124b1c GrowthRPG.exe!UnknownFunction []
0x00007ff698229f04 GrowthRPG.exe!UnknownFunction []
0x00007ff69824077f GrowthRPG.exe!UnknownFunction []
0x00007ff69824084a GrowthRPG.exe!UnknownFunction []
0x00007ff698242c4c GrowthRPG.exe!UnknownFunction []
0x00007ff698254494 GrowthRPG.exe!UnknownFunction []
0x00007ff69ec7ae6e GrowthRPG.exe!UnknownFunction []
0x00007ffbf042257d KERNEL32.DLL!UnknownFunction []
0x00007ffbf0e4af08 ntdll.dll!UnknownFunction []