Welcome and thank you for posting here in the Community. It's my pleasure to help you today!
As of now we haven't received any reported issues about the customers and vendors search field in QuickBooks Online (QBO). To give you the right amount of information and solution to your concern, may I know what happened to the search field for customers and vendors?
Some issues that you encounter with your QBO account can be solved by opening your account using a private or incognito window, clearing the browser's cache, and using another supported browser. To start, open/access your account using an incognito or private browser. You can use either of the following shortcut keys:
Google Chrome, press CTRL+ Shift + N
Mozilla Firefox: press CTRL+ Shift + P
Internet Explorer: press CTRL+ Shift + P
Safari: press Command + Shift + N
If it works properly using the private browser, you may need to clear the cache of your regular web browsers. You can also try using another supported browser to help us narrow down the cause of this unexpected behavior.
Please update me with the result by dropping a comment below. Glad to help!
Re: What happened to the Search field for Customers and Vendors?
Until recently the customer search results showed the parent customer. This change has now made it very difficult to find customers with multiple accounts under different parents. Previous search also generated all the accounts that matched the search string with the amount owing displayed.
We have had complaints from customers because it takes so much longer now to find their correct accounts.
Thank you for reaching out in the Community. I'll be sure to point you in the right direction today.
If you've already tried the troubleshooting steps provided by my colleague Angelyn_T, I suggest contacting QuickBooks Online Support. They have the tools to isolate the issue and get to the resolution quickly so you can get back to business again.