Space centre button and "no target"

[Leopard]

Annoyance from today, fly a mission, complete it, brush the debris off and paint over the scratches, then decide to go back for my reward.

Click "Space Centre", nothing, click again and it now flashes up "no target", then nothing. Rocket isn't thrusting, just unable to exit the flight back to KSC - 'quick save' doesn't do anything, the 'space centre' button on the pop up menu doesn't do anything either.

Also unable to quit to the start screen for the game, button just does nothing.

Tried setting a target, which works, then clicking "space Centre", which unsets the target, says "no target" then does nothing.

Only way out is a console reboot (or launch another game, wait and restart KSP.

Have had it a few times, today also got locked in the mission control page, unable to exit.

Is there any other non-obvious way back to KSC?

Did a bit of google-fu, lots of people suggesting to press F4, which is obviously not possible on the eggbox