Why won’t QuickBooks let me add customers

I'm here to assist you with the issue you're facing when trying to add customers to your QBO account, Tyler.

Could you please confirm if you encountered any error messages while attempting to add a customer? Providing additional information will help me offer you an accurate solution to resolve the problem.

In the meantime, you can perform some troubleshooting steps to determine what's causing the QBO system's strange behavior. 

The performance of web browsing can be affected by the accumulation of cache. To clear this out, you can sign in to QuickBooks using an incognito window or private browser. This mode does not save the history of visited websites, which may cause the software to operate oddly.

You can use the following shortcut keys:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Safari: Command + Option + P

Log back in to see if you can successfully add the customer. If you do so, let's clear the cache in your browser to start fresh and ensure optimal performance. If private browsing isn't successful, I suggest switching to a different supported web server as an alternative option.

I'm sharing this article on managing customers for additional reference: Add and manage customers in QuickBooks Online.

Furthermore, you can check this link on fixing errors when you add customers that already exist in QBO: Fix the error "Another customer, supplier, or employee is already using this name".

I'll be around if you have further concerns about managing customers or related issues. Have a good one!