Hi Zoë,
Thanks for reaching out! Currently, I don't believe the Athena query supports requests more granular than daily, so we are unable to get the timestamp data necessary to group results by hours at this time.
When you enable the Cost And Usage Reports, it unfortunately does not gather historical data. We have found that the way to go around this is to submit a support request ticket to get AWS help to backfill data into the CUR.
Regarding your last note about certain dates being skipped, this sounds like odd behavior. Can you please make sure you have your cache files cleared before running, and make sure you are running with the same groupBy parameter each time? We are looking to potentially refactor our cache logic, but in the meantime, you could also use the ignoreCache=true param.
Thanks,
CCF Team