Hi there, @catrin-gleaves.
This might be a web-based issue when running Intuit sites. This will resolves by refreshing the page and clearing the browser's cache. Here's how:
First, access your QuickBooks Online (QBO) account in a private window. This allows the program to run without storing cache or cookies that might cause some problems. Please refer to the keyboard shortcuts below:
Google Chrome: press Ctrl + Shift + N
Mozilla Firefox: press Ctrl + Shift + P
Microsoft Edge: press Ctrl + Shift + P
Safari: press Command + Shift + N
Once signed in, rerun your payroll.
If this works, go back to the regular browser and clear the cache. This will refresh the background process of your browser settings. But, if the same thing happens, use another supported browser.
Also, to know more about payroll processing in QuickBooks Online, you may visit this article: Payroll 101.
Keep me posted if you have any other QuickBooks concerns. I'll be here to help. Have a great day ahead.