I've got you covered on how to handle duplicate non-inventory items in QuickBooks Online (QBO), OfficeSuppliesLtd.
We can make items inactive so they don't show up on sales forms, lists, or financial reports anymore. This doesn't delete the item, it just hides it in the program. Here's how:
- Go to Get paid & pay.
- Select Products & services (Take me there).
- Find the product or service you want to change.
- From the ▼ dropdown under the Action column, click Make inactive, then press Yes to confirm.
Just in case you add an inventory item as a non-inventory item, or a service item as an inventory item by mistake, just change the item type for a product or service. You can check out this article for more details: Change product and service item types in QuickBooks Online.
To learn more about setting up product and service items you buy and sell, refer to this article: Add product and service items to QuickBooks Online. If the same thing happens, we can log in to your account using an incognito browser. Private browser prevents saving cache and cookies that sometimes cause unusual behavior when running frequently visited websites. Here are the useful shortcut keys you can use to access one:
- Ctrl+ Shift + N for Google Chrome

- Ctrl + Shift + P for Mozilla Firefox
and Microsoft Edge 
- Command + Shift + N for Safari

Once done, create an invoice again using the inventory items. If it works, return to your default browser and clear its cache. Every so often the cache becomes overwhelmed with older data which can potentially cause viewing and performance issues. Clearing it will refresh the system, and you'll be able to work with a clean slate. Switching to another compatible one to help rectify the issue.
As always, feel free to read the topics from our help articles in case you need tips and related links while working with QuickBooks in the future.
If you have any other questions about your products and services, leave a comment below. I’m more than happy to help. Have a good one!