Grove Base Hat has no I2C address

One of my Grove Base Hats is not showing its own 0x04 i2c address - however other i2c devices connected to it can be detected (the 28 in this case):

$ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- 28 -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- -- 

Also I have a second Grove Base Hat and the i2c address of that one shows up correctly using the same Raspberry Pi. I think the problem might have been caused when I ran the installation scripts for a GrovePi+. At the time, I didn’t notice that that is a different product. Therefore, I wanted to reinstall the original firmware of the Grove Base Hat. I found the firmware here:

However, I don’t know with which command I can reinstall the firmware. Can you please tell me the command for reflashing the firmware?

Hey, I’m having the same problem. Did you end up resolving it?

Same problem on RPi Zero … 0x04 address is system reserved

Similar (?) issue here. Suddenly all my connected devices stopped showing up (0x08 still shows)