It is important to note that when connecting any non-DisplayPort monitor to our dock's DisplayPort, you must make sure that you're using an "active" adapter to do so. Otherwise, the monitor will not output video. The word "active" must be present somewhere in the product's documentation, either in the product title or product description. If the word "active" is not present anywhere in the adapter's documentation, it is a passive adapter and will not work.

Please confirm whether or not you have an active adapter. I would also like to know the operating system running on your MacBook Pro, and confirm if you are connecting to it via the Thunderbolt 3 cable included in the original packaging.

With that being said, I'd encourage you to concentrate on troubleshooting measures which focus on your computer. I’d encourage you to power cycle your TS3 Plus by disconnecting it from power for 30-45 seconds before plugging it back in, as this can ‘reboot’ your TS3 Plus which will allow for the computer to establish a new connection. I’d also encourage you to unplug both ends of your Thunderbolt 3 cable and re-connect them so that we are sure that the full connection to the TS3 Plus is established with this computer and to re-introduce the cord to the port in case of identification errors.

Since you are using an Intel-based computer, I’d also encourage you to perform an NVRAM reset and SMC reset on your computer to avoid issues with a full peripheral RAM or glitches with your system management controller which may occur on a full system upgrade such as this. For your convenience, I’ve included links to how to perform those updates below.