Using Siri with SENA 50s motorcycle bluetooth headset

Hi,

I have an iPhone X and have been using Siri successfully with a variety of bluetooth headsets. For example, I have a Plantronics Voyager 5200 that I use with my iPhone every day. Siri works great with it. But I can't seem to get it to work with my newest bluetooth device - a SENA 50S. The 50S is a motorcycle headset that accepts voice commands via "Hey Sena", "Hey Siri" and "Hey Google". The "Hey Sena" commands work well. But when I say "Hey Siri" she starts up with two tones and then, before I can get another word out, immediately shuts down with two tones. I have reached out to Sena for assistance but I thought someone here may have already encountered this and have a solution.

Thanks!