Freelancers: what’s the most annoying part of tracking time and sending invoices?

I’m launching TimeBill tomorrow. A private, native Mac app for turning tracked work into PDF invoices and timesheets.

I built the first version around a simple workflow: track billable work, organize it by project, export timesheets, and create invoices without moving everything into a cloud dashboard.

I’m curious: what’s the most annoying part of your current time tracking / invoicing workflow?

For me, it was always the gap between “I tracked the work somewhere” and “now I need to turn this into a clean invoice.”