Allow me to take over for a moment. I'm here to share some update about the issue you're getting when running a report and grouping it by class in QuickBooks Online (QBO).
This has been reported as an ongoing issue with QBO and our product developers are still working to fix this as soon as possible. I tried to check with our Support Team to see if there are any updates with this issue and there are no updates yet.
Since you already contacted them, rest assured that you'll receive an email notification once an update is available. I'll also update this post as soon as I get a message from them that this has been fixed.
Thank you for your patience while we work to resolve this issue for you. Don't hesitate to leave comment below if you have additional questions. I'm always here to answer them.