Accents ("?") gone after using the Hummingbird plugin

Dear WPMUDEV,

just tried out hummingbird to increase my site speed which was pretty slow thankfuly the lot of JS used by my Divi theme. Unfortunately after turned the plugin on I have lost all my "?" fonts of the base font I use for the theme. After I have turned the plugin off the "?" shows correctly again with the Dosis font.

Is there any way I coud fix this?

Thank you!

Matthew