I did purchase the RockPi 4 with 16GB eMMC and adapter. When I want to flash the image on eMMC with the adapter it does not recognize the flash memeory.
I can say, I am lucky, since I own HardKernel’s MicroSD adapter from my previous device Odroid C2. Well this adapter works and the image was flashed.
So, why the official SD card adapter doesn’t work? Who is going to send me a functional one?
No, it doesn’t work. As said the HardKernel apapter works, no problems. Raspberry SD card works, no problem. Your adapter doesn’t work. I have to mount your’s eMMC onto a HardKernel’s adapter to be able to flash or read.
I had the same issue when I purchased 3 Rock Pi 4B’s with the eMMC reader. It simply does not work. I’ve tried multiple SD adapters and methods of connecting and nothing. Judging by this thread it sounds like they have a high failure rate. I raised the issue with support nearer the time of purchase but after they got me to jump through a bunch of hoops to prove it was faulty i.e. sending pictures, writing descriptive text of my methods, posting it back to China, I lost interest as it wasn’t worth my time over a $3 piece of nothing. The Rock Pi freezes when I try to dd an image from the OS (booted via SD) to the eMMC so my next attempt will be to find a USB A to USB A cable and install the the eMMC via OTG. The fact that this cheap little eMMC reader hasn’t worked has wasted a lot of my time.
These sorts of things tend to have a lot of problems with SD Card adapters; I’ve had failures with the Hardkernel, FriendlyArm and Radxa units when trying to use them through an uSD->SD adapter, but using them direct in the slot of a multicard->USB adapter (with dedicated uSD slot), they worked properly.