QuickBooks Point of Sale, process and verify or connecting the on-hand item quantities in your inventory by doing a physical count. To learn more about the process of performing Physical inventory, you can check out this article: Perform a physical inventory.
To verify why these items are not showing up, you'll need to ensure that the date field of the report that you pulled up is correct.
I've also added here some articles that you can visit about managing the Inventory report and fixing common inventory accounting issues in POS and QBDT:
I can assure you the best way to get in contact with our Point of Sales team is by following the steps @MaryAnn_E provided above. I confirmed that the number does work, and their hours of operation are Monday through Friday 6 am - 6 pm PST and closed on the weekends. You can also try the chat option on the same page as their contact number to get in touch with their team.
Feel free to let me know if you get in touch with them. I'll keep an eye out for your response.