Different Task Behaviour results in different actions

[AndrewHargreaves2]

Hello Jason Camerano‌, Amir Bar-Maor‌and the ArcGIS Pro Tasks ‌team.

As I wrote about in this post I have a tasks that looks to append data‌ from a featureclass to a featureservice. As part of this I configure the field mapping for a field as shown below:

If I manually step through this step I get the desired results. However, if I set the step to be automatic (as there's no need to interact with it) the above fails to occur. Please can I seek clarification on if this is expected behaviour?

Thanks