This months payroll shows as complete (and has submitted the FPS and created payslips ok), but no journals have been posted to the liabilities or bank account?

Hello there, @support48.

I've found that there is an ongoing investigation about QuickBooks Online (QBO) not creating journals for payroll. Our engineers are still working to fix the issue.

To add your company to the notification list, I'd suggest contacting our Customer Care Team. After that, you'll receive email updates about the investigation's status and its fix. Let me guide you how. 

1. Click the Help (?) icon.
2. Enter in the search field your concern
3. Tap the Contact Us button.
4. Select Get a callback and fill in all the necessary information.
5. Choose to Confirm my call.

Just in case, I'll add this article for future reference: QuickBooks Online Standard Payroll Hub.

Let me know in the comment section if you need further assistance working in QBO. I’ll be right here ready to help. Have a good one.