I can confirm that it also happened on True Fire to a smaller degree, due to the much smaller catalog. I called up and was able to talk to someone (imagine that!), who told me they lost licensing to those songs. I don’t want to name them because my memory is not good,(maybe Hotel Cali and For What It’s Worth??) but they give the option of buying the DLs. At first I thought, no way, but the voice on the other end said, they’re yours forever. They’re about $5 each, give or take, and they have sales all the time so I thought, why not? I can also print/save tabs.  Now I own the DLs and don’t wonder if the songs will be there when I log on.