Entering a soundcloud piece into W2G breaks the room. It will sometimes play for one person or another, but it does not sync properly for all participants. A workaround for those that do not play has been to click on the soundcloud link and load the site directly. Once it is loaded, W2G seems to be able to handle the syncing just fine.
I know soundcloud is fairly draconian with their traffic (not allowing mobile browsing outside of the app) so this may be an issue with them directly.