NoBull: Cannot select my connected/linked table from "Select Reference Connect"

I'm going through a pretty typical workflow here of mapping Airtable to Webflow with the NoBull Airtable Extension.

1. I have a created two tables "Blog Posts" and "Categories" with the standard Airtable fields mapped to Webflow fields. All good.
2. I have connected the "Categories" table to Webflow through a NoBull "Categories" Connect--All good. 
3. I have connected the "Blog Posts" table to Webflow through a NoBull "Blog Posts" Connect--All good.
3. I have created a linked field called "Categories" in my "Blog Posts" table which links to the "Categories" table. It works.
4. When I go to map the linked "Categories" field from my "Blog Posts" table to the Webflow Categories field through the NoBull "Blog Posts" Connect, I am select the appropriate Airtable & Webflow fields, but I am not able to do anything with the "Select Reference Connect" dropdown, to connect the linked table--the option is not available to me.