Just noticed this firmware update: HC-X1 Firmware update service | Download | Didital Video Camera | Digital AV | Consumer Support | Support | Panasonic Global (http://av.jpn.support.panasonic.com/support/global/cs/e_cam/download/x1/index.html)

The web page states the update is for:

Correction of the problem regarding the vertical line of 4K mode.
Improved of image quality when using NR control settings.
Improved of image quality when using Cinelike V settings.

I've done the 1.02 firmware upgrade. all went smoothly,nice of Panasonic to allow us to do the firmware upgrades.
I remember years ago when someone "leaked" the firmware for the EX1, which i downloaded, and did the upgrade myself, i remember feeling like it was practically illegal. That was the upgrade that allowed use of SD cards inside sxs adaptors, instead if the hugely expensive sxs cards.

Paul.

Part of this firmware should have fixed the Cinelike V issue reported here:

https://www.hdwarrior.co.uk/2016/12/07/the-panasonic-hc-x1-video-review/

Version 1.03 is now available, but it seems it is only to correct a language issue in the menu.