CB2 + PI4B adapter board unable to flash eMMC via RKDevTool

I want to flash my image directly to eMMC via RKDevTool
My setup is CB2 with PI4B adapter expansion board (https://github.com/bigtreetech/PI4B-Adapter/blob/master/Hardware/BIGTREETECH%20PI4B%20Adapter%20V1.0%20User%20Manual.pdf)

Under all available instructions I did:
1. turned ON switch 1 (USB OTG) and 2 (RPI BOOT) on PI4B
2. powered external 5V to PI4B
3. plugged into PC via USB-C
4. installed drivers so when on next USB plug-in I keep SW1 pressed on CB2 and luckily obtain 'Rockusb Device' in Device Manager:

6. opened RKDevTool and it clearly found MASKROM device
7. selected default loader and my image and hit RUN, but I see this:

Logs are like this:
18:19:45 973 Layer<1-7>:Download Boot Start
18:19:58 019 ERROR:Boot_VendorRequest-->DeviceIoControl failed,Total(59394),Sended(16384),bRet(0),err(79)
18:19:58 019 ERROR:DownloadBoot-->Boot_VendorRequest471 failed,index(1)
18:19:58 020 Error:Layer<1-7>:Download Boot Fail
18:19:58 029 Layer<1-7>: RunProc is ending, ret=0

General considerations and search pointed out that maybe 'MiniLoaderAll.bin' is not accurate for my CB2??
I tried several other ones I found in 'https://github.com/radxa/rkbin/tree/master/bin/rk35' and as well in 'https://github.com/armbian/rkbin/tree/master/rk35' but with no luck. Which is correct?

I also see DIP switch on PI4B named NEXTRST with zero explanation, I tried it but seems it does the same that I do with keeping SW1 on CB2 when powering the device. Is there any sequence not mentioned in docs?

My issues seems to be the same to 'https://github.com/bigtreetech/CB2/issues/100'

What am I missing, any idea?

Start with the PI4B adapter manual, the RKDevTool MASKROM logs, and related issue #100. Reproduce the documented switch, power, USB, and SW1 sequence, then compare the CB2 loader candidates in the referenced rkbin repositories. Done means identifying a verified loader or sequence and documenting the working eMMC flashing procedure.

Written by the indexing model from the issue text.