Why is GetAllAnimationSequencesReffered Editor only?

I needed to get the length of time for a Montage, and there was not a function that just returned it, so I was using GetAllAnimationSequencesReferred and adding up the time for all the sequences. Things were fine until I tried to build for development only. Then it would not.

UAnimMontage line 306.

#if WITH_EDITOR
// Begin UAnimationAsset interface
virtual bool GetAllAnimationSequencesReferred(TArray<UAnimSequence*>& AnimationSequences) override;

How, in C++ are you supposed to get the length of time for a Montage?

Pointers of type UAnimMontage has a property called SequenceLength, so

float animLength = YourAnimMontage->SequenceLength;

I guess I was making it way too difficult. Thanks.