My personal take-away is "hold off on buying a Pi4 until this issue has been addressed in a future revision".
it's good to know that it just might not work with some cables though. probably saved a few hours of head scratching in the future for a few folks.
Mine is idling at 64°C now that I took off the official cover; with the cover on, it was idling just below the CPU throttling point of 80°C, which meant that almost any computation caused it to start intermittently locking up.
There was a firmware update, so make sure you applied that. Might help bring the temps down a bit.
AFAIK that firmware update isn't up yet, and won't be for weeks.
There was an update that made a small improvement in idle temp. https://www.cnx-software.com/2019/06/29/new-raspberry-pi-4-v...