No more voice navigation prompts after update to 28.20

I got the update to 28.20 today. Went for a ride afterwards an followed a course. I noticed that the voice navigation prompts that usually play during navigation ("in 300m turn right") are no longer playing on the device. Instead I only get a few beeps when I'm approaching a turning point. I tried all options I could find in the Sound and Navigation menus, but was unable to get the voice prompts back. Is this a known problem? Any fixes? Thanks!