Hi, gcummins,
I have found some further information on this issue. It can occur when the template that is used when the project is begun is something other than the electrical template (such as the construction template). If that might be how this project was started, the fix for that is as follows:
1. Create a new project using the electrical template.
2. Open the problem file in the same Revit session.
3. Using Transfer Project Standards to transfer from information from the new project to the existing project > select none > select Panel Schedule Templates: Branch Panel, and click OK.
4. in the next dialog, choose Overwrite to overwrite the existing parameters
Now you should see the entire panel schedule.
I know you mentioned having used Transfer Project Standards, but in case you did not choose Overwrite, and for the benefit of other forum users, it might be worth trying again.
Please let me know if you need any further help. I'll be happy to have a look at your model if this doesn't resolve the issue. I can send you a private upload link if you'd like.
Looking forward to hearing from you!
Best,
Judy_S