Guild Wars 2

Did you receive items at all? If yes, is it possible that you received a key instead? You either get 3 stones OR a key.

It’s not the only source of Transmutation Stones – you can also buy them in Gem Store.

The only maps that guaranty to get you transmutation stone are the race main city including lion arch. The other map will give you either a key or 3 transmutation stones. I have 57% map completion and have 40 TS so far and that’s for a single character only, so don’t worry about not getting enough of it although you will need a fine transmutation stone for level 80 items.