The issue with adding additional reports in the Builder has been resolved.

A fix has been applied and we are monitoring the results. Everything is looking great so far.

We have identified the issue. A recent bug fix changed a rule. Fixing shortly.

We are currently investigating this issue.

If you need to add another report in the meantime, you can duplicate an existing report and change the data source.

Steps to do this:
Report Dropdown > Duplicate Report > Data Settings > Data Source > Change