When creating new invoice it will pull all unbilled activity (time/expenses on finalized and pre-bills are excluded). So in this case, if you make an invoice and some of the time is not pulling in you might already have a pre-bill sitting out there for this client. To check, follow the steps below:
- Click Invoicing from your blue menu bar
- Click on the Find Invoice button
- Pull down the "Client" drop down to the right to choose this particular client
If there is an Open pre-bill sitting there then click into it and Delete it (or them if there are multiple). Then go and create your invoice which will pull in all of those unbilled items.