I’ve run into the same issue with three Pan Cams not accepting a manual flash. I was able to successfully get a fourth to flash. The different I found between them is that the one that did accept the flash appeared to be an older production unit (new, but old box, earlier serial). I also found that, encoded in the QR code in the back, the unit that accepted the flash has code D00A000 in it, versus the three units that did not accept the flash has the code F00A000 encoded in the QR code. (Can you scan your QR code of your unit, and see what the middle string is between the pipes, |'s )
A hardware revision has not been confirmed by Wyze, so this is just my theory right now.