LG TV "Check Signal Cable" over HDMI

I recently purchased an LG 24LH4530 to use as a third monitor. However, when I connect to its HDMI input through the UD-3900, the TV only displays a blank screen with the “Check Signal Cable” message bouncing around the screen. Interestingly, in my laptop’s display settings, it shows the LG TV as a third monitor and allows me to try to customize the display settings, select resolution, etc.

FWIW, I am using the DVI port with the DVI-to-VGA adapter to display on an HPLE2201w.

  1. This exact setup works with my Samsung TV. If I merely swap in the LG TV, the LG TV will not display.
  2. If I disconnect the HDMI cable from the dock and instead plug it directly into my laptop’s HDMI port, then everything works as intended. The display settings are identical -> 1366 x 768 (recommended) resolution, 60 Hz.

The cable is fine. The TV is setup to display from the correct HDMI port. I’m using Windows 10, and Windows believes I have the latest driver for UD-3900. Still, it seems something between Windows, the UD-3900, and the LG 24LH4530 must not be right.

Any ideas about what I might try?

Thanks,
Matt