I'm using a Lumia 640 LTE, Windows 10 Mobile
Garmin has the Connect app that works on my phone and will sync the device.
This was a key item for me buying the Garmin, was sync function for my Windows phone, no problem with the BT connection. The only thing I would say is that it tended to use more battery that I was used to. Had to trim back how much the app used, or how often is sync'd up.