grouped windows don't get clipboard input

ubuntu 18.04 terminator: grouped Windows in terminator get input at the same time if keyboard is typed in one of the grouped windows and "group send" is active. Using the mouse and clipboard to input text results only in input in the "primary" window. The other grouped windows do not receive this input.
I moved some months ago from ubuntu 16.04 to 18.04. This behaviour seems to be new. Terminator in 16.04 multiplied the clipboard input to all group members with active "group send".

lsb_release -rd

Description: Ubuntu 18.04 LTS
Release: 18.04

terminator:
  Installiert: 1.91-1
  Installationskandidat: 1.91-1
  Versionstabelle:
 *** 1.91-1 500
        500 http://de.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
        500 http://de.archive.ubuntu.com/ubuntu bionic/universe i386 Packages
        100 /var/lib/dpkg/status