API Support wrote:
The message just means that not all data within the interval has been formed yet. For instance, if at 12:30:00 GMT you read ticks for period 12:00:00 - 13:00:00 GMT then only existing data will get read. And if you read for the whole day 4 hour bar data at 12:30:00 GMT, then only the first three bars will have been formed and consequently will get read and you will receive "Not all data was loaded for interval".
Thanks for information. The problem was on my side. It was unusual long trade. Sorry.