I do have a few different tags with me, on sticker format, which are 13.56MHz passive inductively coupled NFC, and they all cease working as soon as I stick them straight to my skin.
If I stick them to another plain/thick sticker, and then to my skin, they do work.
Not sure if we are talking about the same ones, but I did got a hold of a few of these, and they did work, but the glue layer was thicker (thus I assumed they worked because the glue layer was insulating it).
That’s what I meant with “bumpy” on my previous post.