Edge 1000 with latest 5.10 firmware, Nexus 6p with latest OTA Android 6.0.0 build MDB08L and Connect 3.1.1.1. See attached screen shots: today's ride (18 November) shows correct date/time on Edge 1000, but the Connect app on the phone shows the ride date as 17 November. The phone has the correct date/time on it - it's getting it from the network. The ride uploaded via the phone to https://connect.garmin.com/modern/ shows the correct date of 18 November.
From the Connect mobile menu, if I select Calendar and then 18 November, I see the ride with the correct date shown. However, if I go back to the menu and select Snapshots, it shows me today's ride with yesterday's date. This behaviour consistently reproduces with every ride I sync via the phone.
I'm in timezone GMT+10, if that's of any significance (actually GMT+11 at the moment, as daylight saving is active).
Ditto with this morning's ride (20 November). Ride date shows as 20 November on the Edge 1000 and on the Garmin Connect web site, but when I start the Connect app on the phone, the initial snapshot screen shows the ride with the date of 19 November.