Welcome to the ODK forum, @PaoloC68! We're glad you're here. When you get a chance, please introduce yourself on this forum thread. I'd also encourage you to add a real picture as your avatar because it helps build community!
This is a documented problem with Kobo. We filed an issue at https://github.com/kobotoolbox/kpi/issues/1863 and it looks like it was merged on March but you're experiencing the same problem.