FFS - Transform Activity, insufficient input product to fulfil the activity requirements

Hi everyone, 

 

I have a use-case where there is a variable number of products created, being processed by a transform activity at 20 products at a time. 

 

This results in an incorrect response when there are less than 20 products, because the transform activity will only accept 20 products at a time. Does anyone have any advice on how I can resolve this?