If you're trying to train a Personal Style and your Lightroom Catalogs are currently stuck loading in the Style Builder screen, please double check the following:
Using Lightroom Classic:
Ensure you're using Lightroom Classic catalogs, and not Lightroom CC.
Catalog Storage:
If your catalogs are stored on a network drive (NAS), it must first be copied onto your computer or an external drive.
Cloud Storage Systems:
If you're using a cloud based storage system such as iCloud or OneDrive, ensure that you have all the files related to your catalog downloaded to your computer.
Build Smart Previews:
Ensure Smart Previews have been built for all of your Lightroom Classic catalogs. You can do this by going inside each catalog, head to menu bar and click Library -> Previews -> Build Smart Previews.
If you've gone through the above steps and your Lightroom Catalogs are still stuck loading, try to open your catalogs inside of Lightroom Classic to check they're still working as expected.
If your catalog is working as expected, you should clear your cache and restart Narrative.
You can clear your cache by clicking Help > Troubleshooting > Delete App Cache
Please note, this will also reset your preferences so you might want to jump back into that menu and re-apply any preferences you had selected.
If the issue persists and you're using an external drive, try to disconnect and reconnect your drive that your catalogs are located on. If you're using a Mac, Narrative can automatically rescan the catalog and drive. If you're a Windows user, there will be a popup asking you to rescan your drive.
If you're experiencing any other issues or the article above hasn't resolved your issue, please contact support via the chat bubble in the bottom right corner.