RECIPIENT_LIMIT_EXCEEDED on new Developer Account with only 2 recipients per envelope

Hi,
  
  Message: You have reached the maximum number of recipients permitted
  for a single transaction in your account. Please ask your administrator
  to increase your limit.

  What we've tried:
  1. Voided and deleted all envelopes on the account — error persists
  2. Created a brand new developer account — same error occurs after ~20 envelopes
  3. Verified only 4 unique recipient email addresses are used across all envelopes
  4. Each envelope has exactly 2 signers, 0 CC — well within the documented 5-recipient per-envelope
  limit
  5. Billing & Usage page shows "Envelopes: Unlimited"

  Account details:
  - Environment: Demo (account-d.docusign.com)
  - Account ID: *information removed due to PII*
  - Integration Key: *information removed due to PII*
  - HTTP User Agent: Apache-HttpClient/4.5.14 (Java/1.8.0_452) (server-side integration)

  Questions:
  1. What is the cumulative recipient limit for developer accounts, and what is the timeframe
  (daily/monthly)?
  2. Is there a way to reset this counter or increase the limit for testing purposes?
  3. Is there a setting in the Admin console to view or adjust this limit? (We couldn't find one under
  Signing and Sending.)

  We run automated e-signature tests continuously and need to send ~50+ envelopes per day with 2
  recipients each. Any guidance on how to increase this limit on a developer account would be greatly
  appreciated.

  Thank you!