Make usable UStruct in details panel

Structures are not allowed to be initialized without initializing all of its members. You have to add a constructor like this.

 USTRUCT(BlueprintType)
 struct FSAnswerText 
 {
     GENERATED_BODY()
 public :         
     UPROPERTY(BlueprintReadWrite, EditAnywhere)
         FText FTAnswerText;
     UPROPERTY(BlueprintReadWrite, EditAnywhere)
         float DelayTime;

     FSAnswerText() : FTAnswerText (DEFAULT_VALUE), DelayTime(DEFAULT_VALUE)
     {
     }
 };

Remember to add the DEFAULT_VALUES, it´s just a placeholder for the answer.

Hope it helps.