Ultimate Facebook: username umlauts

Hello,

I got problems with users signing up through the Ultimate Facebook plugin when they have umlauts in their usernames.

For example “Marion Müller” on Facebook becomes “marion_mller” as username and community-name in buddypress/WP.

Interestingly using the mapping to Buddypress-function of the plugin works: last name “Müller” on facebook creates “Müller” in Buddypress.

What can I do?

Thanks,

Eike