Auto rigging part doesn't work

Hello there,

I am trying to animate Olaf with Mixamo but the auto rigger doesn't recognize the body parts of Olaf and sends me back a error message saying I have to place the markers on the body (which I did...)

The thing is, his arms are so thin that it might be the reason why the auto rigger doesn't work. I also tried the skeleton LOD to no fingers to lower down the skeleton details but I still have the same error message.

Do you know how I can solve this issue please?

Many thanks

Sarah