Having the same issues where it does hot reload but throws the error in Visual Studio. If you rebuild without the editor open their are no errors.
2> Creating library D:\Documents\Unreal Projects\RPG_4_15\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-RPG_4_15-6083.lib and object D:\Documents\Unreal Projects\RPG_4_15\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-RPG_4_15-6083.exp
2> Creating library D:\Documents\Unreal Projects\RPG_4_15\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-RPG_4_15-6083.suppressed.lib and object D:\Documents\Unreal Projects\RPG_4_15\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-RPG_4_15-6083.suppressed.exp
2>ERROR : UBT error : Failed to produce item: D:\Documents\Unreal Projects\RPG_4_15\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-RPG_4_15-8614.lib
2> Total build time: 5.25 seconds (Local executor: 0.00 seconds)
2>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(37,5): error MSB3075: The command ""D:\ProgramFiles\Epic Games\UE_4.15\Engine\Build\BatchFiles\Build.bat" RPG_4_15Editor Win64 Development "D:\Documents\Unreal Projects\RPG_4_15\RPG_4_15.uproject" -waitmutex" exited with code 5. Please verify that you have sufficient rights to run this command.
========== Build: 1 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========