To expand a bit on what Shohei is saying. This is how structs work in UE4.
The absolute minimum you need is:
USTRUCT( )
struct FTestingStructA
{
GENERATED_BODY( );
};
This includes having “F” before the name of the struct, or you will get a compiling error of, “Struct ‘TestingStructA’ has an invalid Unreal prefix, expecting ‘FestingStructA’”.
You need GENERATED_BODY( ), or you will get the compiling error of, “Expected a GENERATED_BODY() at the start of struct”.
Thank you for submitting a bug report, however at this time we believe that the issue you are describing is not actually a bug with the Unreal Engine, and so we are not able to take any further action on this. If you still believe this may be a bug, please provide steps for us to reproduce the issue, and we will continue our investigation.