P2422HE to P2422H, daisy chained, not waking P2422H?

We have recently purchased multiple sets of Dell P2422HE/P2422H pairs for USB-C and DP daisy chain config for our office's PCs.

So happened, one of the set had a P2422HE from a newer manufacturing batch which is using the newer M3B201 firmware, whereas the rest had the older batch of P2422HE using older M2B201 firmware.

We only noticed the firmware difference when that one particular monitor set consistently failed to wake up the secondary P2422H from sleep (blank screen), where as the others had absolutely no problem waking up the secondary monitor. Whenever the monitor set with the newer P2422HE goes to sleep for an extended period of time (over 30 minutes to a few hours), the secondary monitor will always fail to wake up from power-saving mode.

We tried every combinations we can to swap the secondary P2422Hs, cables, and PCs to isolate the problem, and we were able to 100% reproduce the issue regardless of which PC, cables, or which secondary P2422H monitor we used. The wake up failure occurs if and only if the primary monitor is using the P2422HE with the newer M3B201 firmware.

We also tried everything we could on the monitor settings, PC and OS side, we even tried factory resetting the P2422HE, but the result remains exactly the same. This made us believe the issue is most definitely related to the newer M3B201 firmware. However, there is nothing on Dell's official website to let us change/update/downgrade the firmware for the P2422HE. We tried to contact Dell's tech support and their reply was that basic warranty doesn't cover any daisy chain related issue. So we are basically left in the dark. I hope someone can shed some light on this issue. Thanks!

Monitor's OSD menus showing the problematic P2422HE with newer M3B201 firmware.

Newer P2422HE (M3B201) with 2nd monitor wake up issue 

P2422HE with older M2B201 firmware where daisy chained secondary monitors wake up consistently from sleep.

Normal P2422HE (older M2B201)