Customer names not appearing when I use "receive payment" I have logged out and back in again, and the same issue occurs. I cannot search a customer either.

I recognize the urgency to resolve the issue with the customer dropdown, Sam. We've received similar cases and reports about users unable to select a client as the dropdown arrow option is unresponsive. 

As there is no specific timeframe for the resolution, I recommend contacting our Customer Support team so they can add you to the list of affected users and provide progress updates via email. Please be assured that our Product engineers are committed to resolving this issue.

Please follow these steps to reach them:

1. Go to the Help menu, then select the Search tab.
2. Click Contact Us.
3. Choose a topic, then enter a brief description of your concern and hit Continue.
4. Pick either Chat with us or Have us call you and start connecting with them.
    

Moreover, if you need to return your customer's money, you can follow this article to note it in the program: Record a customer refund in QuickBooks Online.

Let me know by commenting below if you have further inquiries about QBO. I'll be here to answer them promptly.