When trying to copy a Nintex workflow, Sharegate displays the following message:
The 'Store attachment URLs in' value will not be preserved in the action 'Fetch data request' because Nintex does not support setting this value when field references are set.
This warning occurs when Sharegate tries to copy a Nintex workflow that has an action with a value for the parameter 'Store attachment URLs in'. The warning will only happen if there are values in the field references of the content type associated to the action. The workflow will be successfully copied, but the parameter 'Store attachment URLs in' will lose its value because Nintex does not support setting both Content type fields and 'Store attachment URLs in'.
Based on the preceding screenshot, the 'Store attachment URLs in' will lose its value 'Meeting Suggestions' after the migration, since there is a value selected for the field named 'Test'. This is unfortunately a limitation in Nintex workflows for SharePoint 2010 and 2013.