yi-hack-Allwinner-v2: Missing timestamp

I have 5 YI Outdoor 1080p cameras all running Allwinner-v2 ha30ga. They were all purchased together at the same time, and all have serial number starting with IFUSY59.

The problem is, the latest camera, which I just deployed, does not implement a timestamp in the video. The other 4 cameras all do implement a timestamp.

I have been trying to determine the difference between the cameras that do and the one that does not implement the timestamp. I have found the following differences:

                                Cams With Timestamp        Cam Without Timestamp
Base Version:                  9.0.26.07_202104231123     9.0.26.05_202011201756
ls -l /home/app/rmm            2249956 Apr 23, 2021 rmm   1979100 Nov 20, 2020 rmm

The “Maintenance” tab on the web page for all cameras says:

Installed: 0.2.2 - Available: 0.2.2    [UPGRADE FIRMWARE]

The “YI App” shows the same “Firmware Version” as is shown on the Maintenance page “Base Version”, as expected. Also from the YI App, the Firmware Version indicates “Up to Date” on all cameras, even though there is clearly a newer release (9.0.26.07_202104231123) for the problem camera. (I assume this is the cause of the missing timestamp, i.e., the older YI firmware.)

Bottom line, I can’t find a way to upgrade the YI Firmware for the problem camera to the 9.0.26.07 version.

Because the /home filesystem is read-only, I also cannot find a way to copy the newer /home/app/rmm from a working camera to the problem camera, which I have a hunch would also fix the problem.

I do not understand how the problem camera came with different firmware from the others in the first place.

Can you suggest a solution for me?

Thanks as always!