Downloading all my songs doesent work

[IMTHEZER0]

Hi, i have spotify premium on my honor x5.
I activated the download function on my song list and spotify starts to download all my songs. After that all songs have this green downloaded button behind them. But if I now restart my phone all the songs have to be downloaded again. Only a few remain downloaded the rest I have to download and download again. this is really annoying. But this only happens to my song list all other albums or playlists I've downloaded remain downloaded. So is there a possibility to change that?