Hello,
The issue is most likely still present, just masked by the older firmware.
I'll ask you to send me the output of this command:
hexdump -C /dev/mtd1
It can be run by logging into the device using SSH, as per the instructions here. The username is root, and the password is the same as for the WebUI.
The output can be sent to me via a private message.
Best regards,
DaumantasG