Hi,
During the initialization process and some basic operations,
except for the read and write process, emmc will always run in 1 bit mode, just like the ISP procedure,
so any operation will have no problems in ISP mode(1bit) or with adapter(8bit), except drop read and write speed only.
Unfortunately you didn't include an image or an error log, so we can't analyze it clearly.
FYI, the best way to clean RPMB is to write a backup of the original FFU firmware,
we have even prepared a Special Task button for that in a future update.
If you look at the log, it seems that the power connection is not optimal,
that might be the cause of the error during the eMMC Firmware update.
B.R