Sales Order convert to Invoice: unbilled projects showing up when they are inactive/no billing available

Sales Order convert to Invoice: unbilled projects showing up when they are inactive/no billing available

Bug? Converting an open Sales Order to Invoice with a customer we have multiple projects going at all times. The pull down of ' unbilled projects'  has an error: inactive projects with no unbilled items--"this project cannot be invoiced because there are no timesheet entries". Then why have we gone thru that exercise?

If Sales Orders were tied to a project then we would not have a multiple list of (bogus) unbilled projects. Please fix as it causes Admin errors!