Can't connect Garmin HRM to TACX Desktop App with TACX Flow


I've just got a Tacx Flowsmart trainer so have started to use the Tacx Desktop App on my windows 10 laptop. The app connects quickly to the trainer with no problems. However, the app cannot see my Garmin Heart Rate Monitor which connects via Ant +. The app shows that Ant+ is available, I've checked HRM is working fine by testing against my Edge 520. I've checked it in Zwift and that is fine. All I get is the "Searching.." widget at the bottom of the Device Manager screen. I've gone through all the options in the App but can't find anything I can change. After lot's of googling I can't seem to fins any solutions to this. I can't believe that it is not possible, so what am I doing wrong please?

Thanks in advance .Jim..