Usage Metrics Report

You can delete this report and create new. Also, switch on the "new usaage report" format as shown below:

Please note that you won't be able to find it as of now, no matter whether you use classic or "New Usage Report" format. 
You'll always encounter the following message when you'll try to view the dataset of the usage metrics report:



As far as I know, recently Microsoft Power BI Portal were running some issues regarding usage metrics which they somehow fixed but I believe they have turned of certain features like viewing dataset of the usage metrics reports.

Solution: 

There are two possible solutions if you would like to build in-house Power BI Audit report capabilities: 

1) View Usage Metrics reports on Power BI Admin Portal (see image below)

2) Recommended one: Use PowerShell script and download all the Power BI Audit Data. Also, you can incrementally store this anywhere you would like and create your own report. I have created for my own organization. 

So, my recommendation is to work for the option 2. this would initially takes time but once done, you can monitor your whole Power BI tenant.