"Failed to download list of available maps, try again later please"

Hi,

about a week ago my Germany maps have suddenly disappeared (others are still there), and I can't download maps any more: "Failed to download list of available maps, try again later please". Rebooting doesn't help.

Any ideas what I can do?

Navigator 2.2.54, Android 6.0.1

Thanks in advance for any pointers,

Stephan