I am a 305 user. After uploading my runs to Garmin I no longer have information about timing, elevation, and heart rate available. This situation is driving crazy. Is this issue happening to you? How did you resolve it?
Is this old history you are uploading from your 305? Could be you've reached the limit and detailed info is being overwritten on the device. Have you sent any of it to Training Center? Can you post a link to a problematic activity?