Unable to add Fixed price projects on the same invoice with a per hour project

Unable to add Fixed price projects on the same invoice with a per hour project

If there is a client who has Fixed price projects, and by the hour projects, you are unable to invoice them for both in one invoice. If a client has multiple projects regardless of fixed price or by the hour project. you should be able to put them all on one invoice at the end of the month and send to the client. 

Also, when you go to Invoice> New> Select a client ONLY the by the hour projects show to be added to the invoice. Not Fixed price projects..