Payload limits in inAppPurchasePriceSchedules

Hi, has anyone successfully scheduled an IAP price change with manualPrices in all territories? I've managed to post changes to individual price points and territories but bulk changes (i.e. 175 territories) returns the following 422 error:

"code" : "ENTITY_UNPROCESSABLE",
"title" : "The request entity is not a valid request document object",

The documentation doesn't include a payload sample, and I'd hugely appreciate it.