Dealing with common errors when trying to hide unbilled expenses can be challenging. I'm here to provide straightforward solutions to help you through this, Ziggy.

Please know that the error message is working as designed. The error occurs when the transactions are linked to an inactive account in the Chart of Accounts. Let's reactivate all the accounts and hide the unbilled expenses tool again.

Here's how: 

1. Go to the Gear icon and choose Chart of Accounts.
2. Click the Gear icon next to the printer icon. Then, select Include inactive.
3. Locate the account associated with your expense transactions, then tap Make Active.

If the issue persists, I recommend running the Unbilled Charges report and editing each transaction individually. You can follow these steps:

1. Go to the Reports.
2. On the Search Tab, type Unbilled Charges report.
3. Filter the Date.
4. Edit each transaction individually.

Moreover, you can check out this article to help you track bills and record the payments in QuickBooks: Enter and manage bills and bill payments in QuickBooks Online.

We're always here in the Community to help if you have other questions about managing unbilled expenses. I'll be here to answer them for you. Keep safe.