I just started 0.4 Beta on PI3. It boots up, but from the first second, the connected screen (normal monitor with HDMI-VGA adapter) keeps flickering. I can somehow see a picture, but something seems to be wrong with the timing. I have also a Pifi digi+ connected at the same time.
Its not a HW issue, because if I boot with another SD card with Libreelec, everything works fine.