OAuth Token Refresh 401 during JMeter Load Test on US1

So I’m seeing a very odd bug with the OAuth token refresh endpoint when simulating high concurrent agent logins.

Genesys Cloud US1
JMeter 5.6
Endpoint: /oauth/token
Config: 300 concurrent threads

Error: 401 Unauthorized - Invalid grant

The initial token works fine, but refreshes fail under load. Is there a specific rate limit for token refreshes that differs from standard API calls? How should the JMeter script handle this?