Using GARMIN 920 XT and RUNNINGAHEAD (Read 89 times)

I work off of 2 MacBook Airs, Yosemite 10.10.2 and have 920XT.

I managed to get my workout history uploaded once, but can't figure out how to do it again.

I continue to get messages that say that the device cannot be detected and to connect it. 920 XT  is hooked up via USB- even though everything transfers to Garmin Connect via wifi. I've disconnected... restarted Safari... Restarted computer... Turn Garm on/off... Attempted Garmin boot block- I couldn't get this to work as directed by Garmin.

Help!  How can I get my 920 XT to sync regularly?

Thanks.

stella