Why can't the "customer search" feature find an existing customer?

Thank you, Elmattango, for taking the time to bring this issue to our attention through the community forum. Allow me to address your question regarding the issue of being unable to lookup existing customers.

We are currently investigating an issue with the search function (INV-96044). Our engineering team is already working on identifying the cause and developing a solution as well.

We are compiling a list of affected users to keep updated on our progress. Everyone on the list will receive status updates and notifications when the issue is resolved. 

Please contact our support team for us to add you to the list. Here's how to reach out to them: 

1. Log in to your QBO account.
2. Go to the Help menu in the upper-right-hand corner to open the QB Assistant window.
3. Type in talk to a human and press Enter.
4. Select QuickBooks Online Support, then click Contact Us.
5. Provide a short description of your concern or provide INV-96044 as a reference. Then, click Continue.
6. You'll see several options on how you want to get in touch with our support team.
7. Select Callback if you want to save your spot in the queue. Choose Appointment to have someone call you in the next available schedule. On the other hand, click Chat if you want to start a conversation with one of our chat support agents.

Thank you for your patience as we work to sort this out as soon as possible, Elmattango. Resolving this search function issue is a high priority for our team. If you have any other questions or need assistance going forward, the entire QuickBooks Team is here to help.