I use QB Online daily, and add new inventory items almost every day. Suddenly, the "Save an Close" button is unresponsiv. Sales tax area vanished from Add screen too??

Thanks for bringing this to our attention, Nashville.

I appreciate the troubleshooting actions you've performed when trying to fix the Save and Close button when adding new inventory items and utilizing the Sales tax area.

Upon checking, I discovered that other users also encountered the same concern. I recommend contacting our Customer Support Team so they can add you to the list of affected users and update you once there's a fix. 

Here's how:

1. Go to Help (?).
2. From the Search tab, click Contact Us.
3. Please enter your question and select Continue.
4. Review and choose from the following: Have us call you and Chat with us.

Additionally, we have various reports that provide immediate insights into your top-selling products, inventory on hand, cost of goods, and more. This will enable you to make informed decisions swiftly and effectively. Check out this article for more details: Use reports to see your sales and inventory status in QuickBooks Online.

The Community is always ready to back you up if you need more help with inventory in QuickBooks Online (QBO). I'll keep the thread open so you can comment back. Take care always.