Summary

Automation or Post functions fail to set/copy the field value from custom field A(Source) to custom field B(Destination) with drop-down field type.

Cause

• All the options that are part of custom field A(Source) and custom field B(Destination) are same, we will still end up seeing the failure as there would be additional spaces in either of the field values.
  
  

Solution

• Solution 1:- Is to copy and update the field options for custom field B manually from custom field A to ensure that there are no additional spaces.
• Solution 2:- Is to create a custom field B with text field format rather than a dropdown field.