The budget that you've created will be shown in the Reports as Budget vs. Actuals.
I'll show you the steps:
Go to Reports.
Enter Budget vs Actual in the Search field.
Once done, you can choose the budget that you'll want to run in the Budget drop-down.
If you're still unable to generate the report, let's perform a few troubleshooting steps to resolve this.
You can use a private window and perform the tasks there. If it works well, go back to the original browser and clear it's cache. Also, I'd suggest switching to a different browser such as Google Chrome, Mozilla Firefox or Internet Explorer.
Let me know if you have other concerns about budgets in QuickBooks Online. I'm always here to help.