Latitude 5480 won't detect Dell Thunderbolt TB16 docking station.

@traveler091  Thunderbolt 3 was an optional feature on that model. The standard offering was USB-C with video output. Are you sure that system has Thunderbolt 3? Go into your BIOS Setup and check the Thunderbolt Configuration section. If everything is grayed out, you don’t have it.

And what size power adapter is connected to that TB16? With a 180W adapter it should be able to supply up to 90W, while a 240W adapter would allow it to supply up to 130W.

Do you perhaps have an extension cable involved here? That could break your Thunderbolt connectivity and cap your USB PD wattage at 60W. And that also would have been good to mention in the first place if so.

@jphughan, Thank you for your reply.

My system has Thunderbolt 3, The TB16 is powered by 240W adapter.

Everything worked has been working fine until last update.

I have updated the laptop's BIOS and the dock's firmware recently, but after that the system has been operating very well.

I don't know what happened. Several days ago the system just stopped recognizing the docking station. In BIOS settings the thunderbolt is set as it should be.

@traveler091  If you haven't already, try disconnecting the laptop from the dock, then disconnecting the dock's power source.  Then reconnect the dock power source and your laptop.  If cycling the dock that way doesn't resolve it and you don't have an extension cable added to the cable from the dock that attaches to the system, it sounds like you may have a hardware problem of some kind.  It would be nice to isolate variables by trying your laptop on another dock and/or that dock with another laptop, but if you can't do that, I'd guess the dock is the culprit here.