Unable to create invoice for unbilled time

Unable to create invoice for unbilled time

The Windows Phone app for Zoho Invoice is wonderful for creating contacts and tracking hours, but the actual invoicing is very nearly useless for anyone in the services sector.  Creating a new invoice is easy, but you cannot apply the timesheet data you just created using the timer feature!

Is there a function I'm just missing, or is there no capability to invoice unbilled time in the Windows Phone app?