Tracking - Ability to set default Tracking in invoice Branding Theme
It would be nice to be able to set a default tracking category for invoice branding themes. As it is now, we have to set the tracking category manually for each line item on an invoice. For longer invoices this becomes very tedious and error prone.

Hi Dominic, as Tracking was originally designed as an internal mechanism for tracking and monitoring parts of your business, it's not possible to make this field visible to your customers (re the invoice branding theme) we have a slightly different request for this here that you're welcome to join if you'd like to see this.
However, if you'd like to set a default Tracking option to save yourself time when entering invoices you could set this on your Contact records. Within the Sales and Purchase sections you'll see an option to assign a Tracking option for each category you've set up.