No keyboard input after opening SSH session unless "grab keyboard input" is toggled

Hello,
I'm currently testing RDM Enterprise on Windows 7 64 bit.
With any default SSH session I have to toggle the "grab keyboard input" button on each session start to get any keyboard input through the session to the remote host.
I already disabled all keyboard shortcuts and switched to the 64 bit client but with no success.
I'm not able to get this working properly.

Here is an example of the procedure:
1. Create a few new SSH sessions
2. Open the session
3. No keyboard input is possible, the remote host does not react
4. Toggle "grap keyboard input"
5. Now the characters are sent throut the SSH session, the remote host reacts
6. Open another SSH Session
7. No keyboard input is possible, the remote host does not react
8. Toggle "grap keyboard input"
9. Now the characters are sent throut the SSH session, the remote host reacts
10. ...and so on.

I hope that there is a simple workaround to resolve that behavior.

Thanks,
Felix