App won`t start from memory card

[cth]

Until yesterday Spotify was working nicely on my Windows Phone (Lumia 720). I downloaded it on the memory card, everything was fine.

Suddenly yesterday, it stopped working and won't start anymore. All I see is the start screen of Spotify. Then nothing happens forever. I deleted and reinstalled app several times. Only worked when I downloaded it to the internal memory of the phone. However there is not enough memory space for my offline music.

what can I do to fix my problem?