I have encountered a couple of problems with the favorites lists.
The first is that the "begin" button beside each item in the favorites list does not work. As a result, I cannot jump to that song or lesson from the favorites list. I have go through an alternative route to get to the selected song or lesson. Defeats the purpose of have a favorite list in the first place.
The second issue I have encountered is that a couple of lessons, riffs for Cocaine and Smoke on the Water, have shown up in my favorites list but when I go to those lessons, there is no "remove from favorites" button to remove them. That button seems to be there for other songs or lessons, but not those ones.