When attempting to search for a Smart field that has Site Security setup for a specific Site in CRM to add a step for the Business Process Parameter set, their are no records returned when filtering based on the Site.
We’re currently evaluating this issue for a fix in a future release.
Steps to Duplicate
Go to Administration > Smart Fields
Select the Smart field type (any should work), click OK
Specify the Name
Go to Parameters tab, select a site
Under Site Filtering tab, mark checkbox for Site filter enabled and specify same site from previous step
Go to Administration > Queue
Click Add to create a "smart fields" queue
Click Add Step
For Business Process Type select Smart Field Process and for Site select the site specified in the steps above, click Search
Note: No records found
Remove the Site and click Search
Note that the smart filed created in Step 4 above is visible