Clarification of my comment 58:
Ubuntu 16.04 LTS with MATE desktop does not affect by this bug,
but 17.10 and 18.04 LTS are affected even with MATE desktop (see bug 1720364).
So Ubuntu 16.04 LTS with MATE desktop is unique, here we can use Ctrl+Shift layout switcher without problems. And of course Alt+Shift too.
Clarification of my comment 58:
Ubuntu 16.04 LTS with MATE desktop does not affect by this bug,
but 17.10 and 18.04 LTS are affected even with MATE desktop (see bug 1720364).
So Ubuntu 16.04 LTS with MATE desktop is unique, here we can use Ctrl+Shift layout switcher without problems. And of course Alt+Shift too.