I am rather envious of your situation sir
I have a Hi10 Pro (PQ64G4216xxxxxx) Z8350 Hampoo Dual Boot with magnetic keyboard. It has developed the dreaded SD card disease. No black screen or charging issues though, thankfully.
It was fine at first, then became increasingly unreliable. Right now it takes many tries/combinations of insert, remove, reboot, restart, etc, etc, to get to see the card in either Windows or Android. However, when a device is this unreliable it is virtually useless in any practical sense in my opinion.
There is nothing wrong with my cards. They work OK in the keyboard USB ports in an external card reader. And as you have discovered, even the no-name cards work.
I don't believe there is anything intrinsically wrong with the hardware or drivers either, even though the Windows driver versions have changed during its various upgrades.
I tend to think it has something to do with the timing of the loading of the resources for the card reader at boot time, simply because it works some of the time. That is, the device is not entirely dead.
From my observations, boot times vary greatly so something weird is happening with the tablet here. Boot times change depending on whether the device is charging or whether the card is present, or whether the card was seen last time. The duration of the last shutdown can vary boot time, e.g. minutes vs hours it was turned off. The method of shutdown option taken, e.g. Alt-F4, GUI, hardware button can vary the time it takes to shut the tablet down too. Trouble is, I can't find a combination that makes the SD card show up every time.
Windows boot parameters can be altered but I am reluctant to change anything for fear of breaking something else. I am not sure anything can be changed much on stock Android.
Intermittent faults are the most frustrating thing to resolve at the best of times but this one is enough to drive the most patient person crazy. It's no wonder Chuwi engineers remain silent on the issue if they have the same models in the same state as yours. I wish I did. If they've got one like mine they are probably well on the way to an insane asylum by now.
Having gone through this experience I would not buy another Chuwi device again, nor would I recommend anyone else do the same. Which is a shame really because the tablet itself is quite good quality and would be excellent value for money if the SD card reader worked 100% reliably. Or even if it worked 99% of the time would be OK with me!!!