Why are brands that I know I’m authorized to sell, not showing up in My Brands?

You may have to de-select the filters in your Brand Explorer (Keystone, SEMA Data Co-Op, ASAP Network in the example below). Close these by hitting the "X" on each:

Once you do that you should find that those missing brands show up as authorized so you can “Add to My brands”:

If you have SEMA data connected but your authorized brands are not showing as authorized you can go to the 

settings tab, select catalogues, select SEMA data, and click the "get authorization" button.