Vehicle state snapshots sometimes returning no data?

Hello,

I'm noticing that sometimes there are random cases where when querying a vehicle snapshot for fuelPercents at a given time, I get no data back.
According to the API, it is suppose to return the data at that time or the last data point before the requested time, however, I'm getting no data back.
Sometimes it's hours of gaps in data, sometimes just a few minutes.
Why does this happen?
The only things I can think of is that there is a limit set between the requested time and the last data point available? Could that be it?