Duration Fields with Pipelines

Are you defining the template from within the pipeline and hardcoding it - or are you pulling from a 'Template' Table? 

I ran a few tests of moving duration from one field to another with no issue. I hardcoded it as it sounded like you were doing and ran into what I imagine is your error. Long and the short is that duration in QB is actually a metric of milliseconds. So if you're trying to populate a duration field via Pipeline and you're hardcoding the template in the pipeline - then you'll need to provide the integer value of the number of milliseconds. So lets say if you are populating a duration of 1 day - then you instead need to pass in the number 8640000. The smart days is just a setting for how to display the underlying numeric value of the duration, so it won't have any effect on the translation within the Pipeline.