Back at home from a 7-week photo trip.
UPDATE: I had another OWC Thunderbolt 3 Dock on hand, which I swapped out—operation restored. The Mini DisplayPort maybe got fried by the PG&E outage? Or maybe it’s just bad physically, as it seems loose and sloppy. At any rate, swapping the dock fixed the problem.
Update 2: it seems that the Dock which drives the display has one bad Thunderbolt 3 port. Or my LaCie Bolt is toast. It’s all very confusing.
UPDATE 3 — SOLUTION: a suggestion OWC: remove power from all devices (unplug), wait a bit and reboot. I’ll be damned—this cured the dead Thunderbolt 3 port and the display works too! Having to unplug stuff from the wall to make it function is just insanely bad, but I don’t know who/what is at fault except that macOS updates seem to have been making all this worse and worse, so Apple is the whipping boy at present.
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On my trip, I inadvertantly installed the latest Apple security update for macOS Mojave (I have not “upgraded” to macOS Catalina, and I don’t plan to for some time, as it will hit me with at least $500 in upgrade costs for various software.
What I did NOT expect is that the latest Apple macOS Mojave update would destroy connectivity to my NEC PA302W, my workhorse display.
I just cannot get the PA302W to work; the PA302W just says "no signal". This after years of bulletproof operation.
The cabling has not changed, it just sat there while I was away: a DisplayPort cable connects the NEC PA302W to the Mini DisplayPort port on the OWC Thunderbolt 3 Dock. This stuff just sat there for 7 weeks, untouched. It no longer works. The only meaningful change was the Apple software update.
Perhaps it is some problem caused by the Apple update that makes the OWC Thunderbolt 3 Dock fail to drive the display now? Or something more basic. But with only two Thunderbolt 3 ports on my 2019 iMac 5K, I have no other options.
This is the worst Apple problem ever. I don’t know what I’m going to do if I cannot get the PA302W to function.