I mean this happens with my mk808b pro every time. Maybe it's only with this device specific issue. It should not happen with others, I guess.
But since nemus has exactly symptom like mine. So I think maybe this situation might happen too.
I'm actually using a "Z9 PRO 4K" from Zenoplige... so not sure how that compares you your hardware. Like I said, booting from the LibreELEC on the SD or USB is fine. My biggest thing right now is seeking out the original Android firmware for the device so I can recover the 3 that I've messed up, so far