I've come with a solution that can help you run a sales report by class and sales rep.
The option to generate a report that shows sales transactions by class and by sales rep in one view isn't available in QuickBooks Online (QBO). As an alternative, you can run the Sales by Class Detail report and export each data that was grouped by class and by sales rep. Then, combine the two data into one Excel file. Here's how:
Click Report from the left menu.
Search for the Sales by Class Detail report.
From the Report period drop-down, select the month you want to show. Then, click Run report.
Review the sales transactions, then click the Export icon and select Export to Excel.
Once done, go back to the report and select SalesRep from the Groupby drop-down.
Then, export it again by clicking the Export icon and selecting Export to Excel.
After exporting the reports to Excel, you can copy the data from the exported one and paste it into the other one to combine the data. This way, you can view the information on one page.