TeamRaiser upsells can be missing when a participation type is not configured to include the upsells.  To correct this:
  1. Go to Fundraising > TeamRaiser
  2. Find the desired event and click Edit
  3. Click Manage Participation Types
  4. Click Edit on the desired participation type
  5. Click the Include Upsells step
  6. Check the desired upsells
  7. Click the Save button or Next button to save