This display issue in QuickBooks Online (QBO) is likely caused by your browser, so let's work together to troubleshoot and fix this, jguns4380.
Let's start by pulling up your QuickBooks Online account using a private browser (incognito). Here's how:
Press Ctrl + Shift + N (Google Chrome)
Ctrl + Shift + P (Firefox)
Control + Option + P (Safari)
Once signed in, go to the Sales menu and select the Customers tab to open the customer's Transaction List and view all your sent estimates.
If all estimates show up, return to your default browser and clear its cache. After that, log out and then log back into your account. This will refresh the system and remove older data that causes viewing and performance issues.
Additionally, after a customer accepts your estimate, you can convert it directly into an invoice to keep your books accurate. Please see this article for the complete guide: Estimate into an invoice in QuickBooks Online.
You can always get back to this thread if you have other concerns about managing invoices and sales transactions in QBO. We in the Community are always ready to help you out.