Thanks for your response, svb. It looks like my problem is indeed an allowance problem but I have been seeing the same intermittent issues as you with various waits/pauses affecting it (I found I needed 2.5 seconds to make a consistent difference).
When I do historical price search from the API companion, all I get back is this: errorCode": "error.public-api.exceeded-account-historical-data-allowance. I can't see that meta data that you reference. Are you able to see this when you use the companion? Are you using a historical price request?