Marked Billable vs Not Marked Expenses

Curious if anyone has found a unique workaround for keeping track of expenses by marked “billable” or not.

Backstory - I work for a cost+ construction company, and each material purchase that comes through our QBO has to be reviewed and marked billable or not to our clients. Now, checking this “billable” box leaves a ton of room for human error, and today I found a transaction that should have had the billable box clicked but it wasn’t. Unfortunately our client’s project wrapped up in August 2022, so we are not comfortable going to them for this $400 expense. After speaking with someone from QB’s helpdesk, I was told that there is no way to filter expenses by marked billable or not. In lieu of re-reviewing thousands of expenses, has anyone found a workaround that has helped them or cut down on this QC process? It seems like like such a glaring issue and I’m surprised it doesn’t exist.

I appreciate the help - thank you!