Is there any solution to this issue? I keep getting an error saying 

"Tax classification feature is not supported. Try again without tax classification code." when trying to change a non-inventory item to Inventory

Thank you for joining the conversation, ARJ2.

Yes, this has been reported recently. However, know that our team has worked diligently to address this issue, and as of December 14, it has been successfully resolved.

Since you're still having the issue, you'll want to remove any cached files that may still trigger the error. This way, you'll get fresh data from Intuit's server. Here's an article for your reference: Clear cache and cookies to fix issues when using QuickBooks Online.

We appreciate your patience as we worked to fix it. If you encounter any further difficulties, please don't hesitate to reach out to me again. I'm just around to help.