On iPhone 6 with ios 8.0 after I updated to TimeMaster 6.0 on 9/27, this bug started.
With this sequence:
Time Entries screen tap +
Add entry screen opens
Choose existing client from dropdown
Choose existing project from dropdown
tap Sessions
tap + to add a session
Screen closes. App is still open and you can see it if you double-click the home button, but new session window never opens.
It was working correctly on iPhone 6 before the TM update on 9/27. I haven't updated to ios 8.0.2,yet.
There is a work-around. If you tap "Save" on the Add Entry screen before opening the sessions screen, then reopen the entry and edit it, you can add sessions.