This is pretty difficult to troubleshoot without seeing how the automation's setup

Could you create a duplicate of your base with no records in it and provide a read only link? That will help a lot with helping you with this, and here's a guide on how to duplicate your base without records as well as providing a read only link:
https://support.airtable.com/docs/creating-a-new-empty-base#duplicating-airtable-bases
https://support.airtable.com/docs/creating-airtable-base-share-links#sharing-an-entire-base

Here's the read-only link - https://airtable.com/appsF92oFdffe1dVi/shrDK7gRuQ4CEY2lZ

I don't think you can see the Automation, so I added the screenshots here

Thanks for your help.  🙏 

Thank you very much for the automation screenshots as well as the link!  I think the issue might be occuring due to the fact that, when we run the "Find Records" step with the "Role Categories Required" field empty, it returns everything in the "Casts and Crew" table

To overcome that I've created a conditional that checks whether it's empty, and if it is it'll just clear out the linked field:

Link to base

Should do what you need now I think!

LOVE IT!!!

I was thinking it was a conditional logic thing, but I couldn't find it.  Thanks so much!  ✌️