After the update/maintenance on Thursday the additional information box says unknown device. The upload via the Garmin Communicator Plugin does say Oregon 550.
Yep I use the Oregon 550t for exercise too. It doesn't include all data, no matter how you upload. It specificaly duplicates your problem with manual uploads and leaves device information blank. Yep manual upload is the only way to get intact accessory data(heart rate/cadence.) If uploading the current track info without saving the track accessory data is left off. If Garmin would implement ANT wireless usb interfacing I think all data would be intact. That doesn't work as far as I know...I have asked on these forums before.
