Problem solved. It was the OpenTasks app.
SOLUTION: In the permissions settings of the OpenTasks app the option “Contacts” (in german “Kontakte”) has to be turned on.
Thanks for your help.
Hello, the app server from Memotoo.com an error when I synchronize. It does not synchronize the symbol €, but in its place put the strange symbols. How can I fix it? thank you so much.
DAVdroid fully supports UTF-8. This must be a server problem, please contact your service provider.