Ki Cad HS Duel 1.3 v 1.5.2 causes drop out from low ber to high BER <30s Pi 4

[2E0WKS]

Hi using multiple of these hats the firmware behaves on pi3b+ upgrading a pi4 hotspot same hat used for over a year a mmdvmcal shows the BER low and then jumps to 30. this has only occurred on this version as the previous beta version worked okay.
Secondly tried roger clarke's and it behaves same way.
I wonder if it is stm32 part of firmware as I have used both your and roger clarke's firmware on these boards without issues.

thanks