No, you're not the only one. I already have the third one and the problem was or is the same with all of them. I threw the first one away because I thought I was being too imprecise with the cleaning. I've had other and older models before, but they never had this problem. So I bought a new one. But it stinks too, just as you describe. I then enquired with Garmin. They put me off with special washing instructions. Strange, isn't it? Of course, this didn't help. I then complained to Galaxus and Garmin. I then received a replacement by return of post. But, as you can imagine, it stinks too. Well, I now live with the fact that wealth stinks and therefore we who can afford such expensive sensors have to pay for it ;D

I have been using the belt for almost 8 weeks now and I mean use. I use it 4 to 5 times a week in the gym and also when cycling. I haven't noticed any odour. I've also showered with it and I sweat on it regularly during and after training. So far everything is fine and odourless

It's true that they have a distinctive smell, as does the yellow HRM pro version.