Advanced Queries allows you to pull data up to the current day with a data processing latency of several hours. This means that there is a slight delay in the data available to pull on the current day; e.g. running a query at 11:00 am for the current day (query end date equal to today's date) will return data from earlier in the morning, but not up to 11:00 am. To see exactly how current the data is in your same-day query, include "Hour" and "Minute" groups to your report. This will display your data in a per-minute time-series.
For this reason, we generally recommend setting your query end date to the previous calendar day at the latest instead of trying to query today-so-far data metrics from this tool.