firebase analytics hourly granularity reports

Question

I'm trying to display hourly reports in the analysis hub of google analytics for Firebase. The option is not selectable and I can't get why. There are only two tapable choices among four: daily or weekly reports.

Since I know it's doable in the web version of Google analytics I was wondering if this is the result of a bad configuration of my apps events or if hourly reports are simply not yet available in firebase analytics.

thanks a lot,