Comment 2 for bug 1537400

Tried Calibre out 2.50, the problem is still occuring.

I started in Calibre in debug mode hoping this might shed some light:

--
calibre Debug log
calibre 2.50 [64bit] isfrozen: True is64bit: True
Windows-8-6.2.9200 Windows ('64bit', 'WindowsPE')
('Windows', '8', '6.2.9200')
Python 2.7.9
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Starting up...
Using proxies: {'http': 'localhost:8118', 'https': 'localhost:8118'}
Using proxies: {'http': 'localhost:8118', 'https': 'localhost:8118'}
Started up in 44.47 seconds with 15 books
  automation interface with iTunes 12.3.2.35 established
Job: 1 Get device information started
DeviceJob: 1 Get device information done, calling callback
DeviceJob: 1 Get device information callback returned
Job: 2 Set library information started
DeviceJob: 2 Set library information done, calling callback
DeviceJob: 2 Set library information callback returned
Job: 3 Get list of books on device started
  Library source: 'Library' kind: Library
Job: 2 Set library information finished
No details available.
Job: 1 Get device information finished
No details available.
DeviceJob: 3 Get list of books on device done, calling callback
DeviceJob: metadata_downloaded: Starting set_books_in_library
DeviceJob: set_books_in_library: books to process= 40
DeviceJob: set_books_in_library finished: time= 0.0220000743866
DeviceJob: metadata_downloaded: updating views
DeviceJob: metadata_downloaded: syncing
DeviceJob: metadata_downloaded: refreshing ondevice
DeviceJob: metadata_downloaded: sending metadata_available signal
DeviceJob: 3 Get list of books on device callback returned
Job: 4 Send metadata to device started
DeviceJob: 4 Send metadata to device done, calling callback
DeviceJob: 4 Send metadata to device callback returned
Job: 4 Send metadata to device finished
No details available.
Job: 3 Get list of books on device finished
No details available.
[0x7FF844B24450] ANOMALY: meaningless REX prefix used