Hello,
after Cubase restart talkback in the control room is always disabled. Does not matter if you left it enabled when closing Cubase or if you saved your control room preset with it enabled.
It is the only thing which gets resetted after Cubase restart and which does not get saved in the Control room preset.
Steps to reproduce:
Hi,
I would expect this is by design.
Why would it be?
You can set up your talkback mic, so that it always runs outside of recording, so you leave it on, to be able to communicate without always having to push a button.
I guess it is so you don’t by mistake say naughty things about the talent in the studio room while your talkback mic is enabled 
Its only because I have it always enabled 
So when I wanna say bad things I just disable it, and hope the artist is not gonna notice it haha
Thing is, if Cubase would remember the last setting it was at application close, like all other settings in the control room, then everyone would be happy. As for people using push to talk anyway, there would be no change.