adress book group problem (proxy mode)

Hello Guys,

we have following problem since the Update to GW 2014 R2 (v.14.2.0 German Client).

In my personal adress book i have created a group called "test" with 5 email adress.
Then i switch from online mode to proxy mode (another account) and send a new email (or appointment) with the test group as recipient.
I sent the email, but i can't delivered (there is no error message).
I switch to sent items and click on the email properties. It displays no recipients and post offices (attachment screenshot).

When i sent the email from my personal account the email is delivered.
I think its a problem with the created group in my personal adress book.

The error exists after the update to R2. Before the update it worked perfect.

Does anyone have an idea?