From the "System Report", looks properly connected & identified:
I'm beginning to think this is an issue with the Drivers and recent updates on HighSierra & Mojave (look for "IOThunderboltFamily"...):
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https://support.apple.com/en-us/HT210919
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https://support.apple.com/en-us/HT211100
With support ending several months ago, I think we're out of luck.