Since a couple of months spotify is not adding any song offline available

[Dbesso83]

Hello, since a couple of months spotify is not adding any track into offline available mode. If I select a playlist or a song turning the green offline available button all the song are showing a grey arrow but the download never starts. Before this issue happened the app used to show the download progress bar in to the top left side of the screen. I use spotify on iPad.
Just a bit of additional info... I have 10gb left of free space in the iPad, I tried to reboot, I looked for update but ios store doesn't show any version upgrade... I am always on 7Mb Wi-Fi connection, 24-7 exclusively available. Can you help? Thanks a lot. Daniel