Fix #2512: Update Rewards Balance Report fetch

[kylehickinson]

Summary of Changes

This pull request fixes #2512

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()

Test Plan:

• Install a fresh build
• Switch to staging environment
• Claim a grant
• Verify that the balance report (rewards summary) shows the claimed grant

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • release-notes/(include|exclude)
  • bug / enhancement
• Necessary security reviews have taken place.
• Adequate unit test coverage exists to prevent regressions.
• Adequate test plan exists for QA to validate (if applicable).
• Issue is assigned to a milestone (should happen at merge time).