If your monitor shows no picture through the Satechi USB-C Multiport Pro Adapter V1 or V2 (AP-PCMPAM), the port or the video cable is nearly always the reason. Video comes only from the HDMI port on the USB-C Multiport Pro Adapter, and the USB-C port on the adapter is a charging port that carries neither video nor data. The HDMI port outputs up to 4K at 30Hz on the V1 and up to 4K at 60Hz on the V2. Work through the steps below in order.

Steps to try

1. Move your monitor cable to the HDMI port if it is plugged into the adapter's USB-C port. That USB-C port is for pass-through charging only.
2. Use a direct HDMI to HDMI cable, which is not included with the adapter. Video adapters and converters may not work reliably.
3. Unplug the adapter's built-in USB-C cable from your laptop or tablet and plug it back in, making sure it is fully seated. The LED indicator lights up when the adapter is connected and powered.
4. Try a different USB-C or Thunderbolt port on your device.
5. Check what your version can output. If you have the V1, 4K at 30Hz is its ceiling, and the V2 tops out at 4K at 60Hz. You can tell the two apart by the cable, which is silicone on the V1 and braided on the V2.
6. Try a different HDMI cable, and connect the monitor straight to your device to confirm the monitor and the cable both work.
7. On a Mac, open System Settings, go to Displays, then hold the Option key and click Detect Displays. Check whether the layout is set to Extend or Mirror, since the two behave differently.
8. Confirm your host device is an Apple USB-C or Thunderbolt device. The USB-C Multiport Pro Adapter is built specifically for Apple USB-C and Thunderbolt 4 devices such as the MacBook Pro and the 2018 iPad Pro (3rd generation), and it is not designed for Windows, Android, or the Nintendo Switch.
9. Install any pending operating system updates, then reconnect the adapter. It is plug and play, so there are no drivers to install.
10. Test the USB-C Multiport Pro Adapter on another supported Apple device. If the display works there, the original device or its port is the problem. If no display works anywhere, the adapter itself is at fault.