Garmin Express 6.5.0 - Later today, 6.5.1!

As a pleasant change from Garmin's usual roll-out, the changelog data is available already.

PC:

Garmin began rolling out Garmin Express v6.5.0 for the PC today. If you would like to update to the latest version, please visit the About page within the Settings of the Express application and select “Check for Updates to Express.” This version includes the following changes:
Express indicates a new device has been connected by displaying a banner. Also, for users who have had to send in their device and received a replacement, Express will detect that it’s the same model of device and ask if you’d like to replace the already added device or add it as a new device.
Improvements have been made to the Help Pages for adding a device.
Fixed an issue that could cause the time to change on a Forerunner 645 after being synced.
Other minor bug fixes and improvements.

Mac:
Garmin began rolling out Garmin Express v6.5.0 for the Mac today. If you would like to update to the latest version, please visit the ‘About Garmin Express’ page from the Garmin Express Menu and select “Check for Updates to Express.” This version includes the following changes:
Express indicates a new device has been connected by displaying a banner. Also, for users who have had to send in their device and received a replacement, Express will detect that it’s the same model of device and ask if you’d like to replace the already added device or add it as a new device.
Improvements have been made to the Help Pages for adding a device.
For some of our fitness devices, Express would indicate a sync failure, even if an activity synced successfully. The sync failure will no longer appear unless it’s a valid failure.
Fixed an issue for our users with devices that have a microSD card slot. A failure would occur when attempting to install an update or downloadable content, regardless if it was to the internal memory or the microSD card.
Please note: This version of Express for Mac requires a minimum OS version of 10.11, including all future versions of Express.

Later today it's 6.5.1 for the PC with no changelog yet.