Volumio 2 and MPDROID cover-art


first of all congratulations on developing Volumio 2.
I just bought an Pi 3 Model B and 3 minutes after installation of the image 2.246 I was able to listen music through my ODAC DAC.
The web interface runs smart and looks fine to me.
But I´m missing a cover wall for my Tablet PCs as in MPDROID.
I tried MPDROID and it works as in version 1.55 but without covers. I don´t know what to put into the music path directory. I am trying for hours now, but no luck. I see every album and every title, but all covers are empty. The FAQ are not helping me.
Does anyone control Volumio 2 with MPDROID?

Greetings from Lower Saxony