Panasonic just released a minor firmware update (version 2.1) for the Lumix G7 and Lumix GX8. The improvement concerns 4K Photo and more specifically the 4K Burst mode:
The frame of AF area is displayed in 4K Burst mode (except when the auto focus mode is set to [49-Area] or [Custom Multi]).
This means that during the 4K burst, the AF area remains displayed on the EVF/LCD while before it would disappear as soon as you pressed the shutter release button.
You can download the new firmware from the Panasonic website by following this link. Click Accept at the bottom of the page and you will be directed to a second page where you can choose the firmware for your camera model. Once you click the correct model, a new window will open and you can download the Windows or Mac version. Don’t close the other page because it includes all the instructions to update the firmware, so read it carefully. Remember to always use a fully charged battery and to format the SD card inside the camera.
We updated the firmware to version 2.1 on our GX8 and it works fine.