TS4 dock suddenly no longer found on Tahoe 26.3 mac mini

I have a 2024 M4 Pro mac mini running Tahoe 26.3. I updated to 26.3 around the time it came out, so this arrangement has been stable awhile. I have a TS4 docking station with the original Caldigit TB4 cable running into the back of the mini (one of the three TB ports).

The mini + TS4 were running great, no problems. Every port was in use and becoming spaghetti, so I powered everything down and did some cable management. I plugged everything back in, and the Caldigit didn't connect. No light or anything. The Caldigit utility is now saying "Found no Caldigit docking stations." Here's what I've done so far:

* confirmed everything was plugged in.

* confirmed the Caldigit cable goes from the "computer" TS4 socket on the dock to one of the TB ports on the back of the mini. I tried all three ports.

* removed all accessories except for keyboard, mouse, and one monitor, all connected directly to the mini (monitor through hdmi, keyb and mouse through the front usb-c sockets

* installed the latest docking utility

* installed the latest firmware I found 2.9, including the process of unplugging the TS4, installing the firmware, and plugging the TS4 back in. No security prompts or anything, zero notifications

* I powered-cycled the mac mini several times.

* I unplugged the TS4, let it sit for a few minutes, then plugged it back in and repeated everything above. No luck :(

* Checked the security settings. It looks like the mini doesn't have an "accessories" setting.

Is there anything else I can do? Again, this was abrupt. It was working fine, then after a power cycle and a few minutes of cable management, it won't connect.