33 minutes ago, gregkinney said:

No strange log entries with the new extension cord. Is it safe to assume there is something wrong with that specific extension cord? And if so, is there any concern for safety? Am I ok to keep using it for other things or should I throw it away?

When I looked at this previously, I attributed the on/off behavior to activity on the power line + the load.

When you tested with the "new" extension cord, was the LL plugged into the same outlet?  If so, that's rather damning.  You might want to give it a little more time to increase your confidence.

After that - extension cords are cheap.  I would cut the ends off (make sure no one else tries to use it) and dispose of it.

Yes, I replicated everything as before. Same LL, same outlet, the new (used) cord in the same position as previous. I will give it the weekend and then follow your disposal instructions. Good suggestion BTW. A conversation I had years ago with an insurance claim adjuster said the majority of house fires he dealt with were the result of cheap extension cords.