Garmin Express Error When Pairing - Device Found, Unit ID Invalid

Loaded up the new Garmin Express last night and tried to pair my FR70.
It can find the device, but then says that there is no serial number and "the specified unit ID is invalid".

It will not let me proceed with the pairing and forces me to ignore the device.

I had excactly the same problem with my FR70's, however I also had a spare ANT-USB, from my girlfriends whatch,
we only use one key as we sync via same computer.

When I plugged in this extra key, the whatches were found, but now shows serial numbers and I could add the devices
and sync via Express as intended.

It is a bit odd since the 1st key has been used with the ANT agent for almost a year and as recent as yesterday.

My very uneducated guess would be that possibly the ANT Agent/key is still holding on to the serial numbers
and not allowing Express access to them, and thats why a new USB-key (clean slate) allowed me to continue?

Anyway, using a different ANT-USB worked for me.

i dont have a different key to use.
I've simply resorted to using ANT Agent until Garmin is able to come up with a fix. You know that saying "if it aint broke"....

I dont know if anyone has found switching ANT USB keys has made a difference. The key is working, the fact that I can plug it in and it can see the device, just cant see the serial# and therefore shows up as invalid tells me there is something else going on.

I've tried to make it work on three PCs, no success.
Sad but true, like LAMOEL I could 'solve' the 'problem' by using another ANT+ Stick.

The same error here. I tryed it with three different USB sticks and two different PC and the same error always. GE works fine with 910 but i got this error when pairing my FR50.

However, i haven't find some help on internet. What's going on with Garmin??

Same error here with 310XT. I can't get Garmin Express to synch with my account and now I can't create workouts and upload them since the Ant Agent doesn't seem to allow that anymore. FRUSTRATED!!

Possible solution.. I had the same error

Same error, on my iPhone and Garmin vivofit.
I rebooted phone, hard reset and it booted up then synced no problem.