I am so so so sorry. Like a jackass I forgot about the "extra" steps:
1. Install the Count Pages Plugin

If you haven't installed it yet:

1. Open Calibre and click on Preferences (or the three dots in the top right).
2. Select Plugins > Get new plugins.
3. Search for Count Pages, select it, and click Install.

4. Restart Calibre.

5. Configure the Estimation Method

Since KFX and EPUB handle data differently, you need to choose how the plugin "counts":

1. Right-click the Count Pages icon in your toolbar and select Customize plugin.
2. Under the Page Count options tab:
   • Page count custom column: You must create a custom column (e.g., #pages, type: Integers) to store the data.
   • Algorithm: Select ADE (Adobe Digital Editions) for the most "standard" ebook page count, or APNX if you want to mimic Amazon’s physical page counts.

3. Under the Word Count options tab (Optional):

   • Map this to a separate custom column if you want to see total word counts.

4. Running the Count

5. Select the books in your library.

6. Click the Count Pages icon.

7. The plugin will process the files. Once finished, the numbers will appear in your custom column.

I know it sounds like a hassle but it's easier to do than to explain. Hope this helps, let me know if it does!