https://developers.google.com/android-publisher/api-ref/rest/v3/purchases.voidedpurchases/list
Is it possible you are making an error in how you’re specifying either of the parameters? What does your request look like?
startTime
string (int64 format)
The time, in milliseconds since the Epoch, of the oldest voided purchase that you want to see in the response. The value of this parameter cannot be older than 30 days and is ignored if a pagination token is set. Default value is current time minus 30 days. Note: This filter is applied on the time at which the record is seen as voided by our systems and not the actual voided time returned in the response.
endTime
string (int64 format)
The time, in milliseconds since the Epoch, of the newest voided purchase that you want to see in the response. The value of this parameter cannot be greater than the current time and is ignored if a pagination token is set. Default value is current time. Note: This filter is applied on the time at which the record is seen as voided by our systems and not the actual voided time returned in the response.
Perhaps you’re specifying a value which is out of the expected range?
At the bottom of the page there is a “Try this api” section so you can try out parameters in their form, so you can see if you’re making some kind of mistake..