U2724D, macOS firmware updater M3T103 not detecting monitor over USB

I am hoping this post helps fellow users like me. I struggled to update the firmware for my U2724D monitors. Using the service tag, I was able to identify the download file. I followed the instruction to all details. However, the firmware updater was not able to detect the monitor over USB. I have tried several known-good cables. My support guy from IT department was able to do exactly the same on his side, no problem there.

After going through all possibilities, I started to look into the files installed by Dell's firmware package. Then I noticed the package has two folders. One for MT103 under folder "74", and one for M3B103 under folder "62". I was able to run "Firmware Updater Launcher" or the "Firmware Updater" under "62" to detect and update the firmware for my monitors.

I guess my monitors are "B" version, not the "T" version. But why didn't Dell document this difference? Why on earth did the support page guide me to M3T103 firmware update using the service tag? There was only one application visible in the Launchpad, but it doesn't work!