MacArthur hat with power module powerdown issue?

[Sailoog]

Good to know, thanks.

[itsyaw]

I am having the same poweroff / shutdown problems as already posted and I've tried all of the above (tidying up the config, disable splash screen etc.) without success. 

Setup :

McArthur hat (with power module and pre-soldered pins) 
RPI 5 
NVME Base (booting from this)
Openplotter v4
Power switch triggered from the NMEA2K power.
Did not install GPIO through openlotter setup (I did install after experiencing the issue to see if this made a difference but as no difference, I uninstalled again)

Canbus and Serial ports configured as per installation instructions for RPI5 
Shutdown on GPIO16
Poweroff on GPIO20
(these were free)

As of this post I believe Open plotter is still working through changes to accommodate the RPI5 - eg GPIO is currently  showing as in beta for the RPI5.  Just wondering is this most likely the underlying cause or another cause related to the previous posts?

Mostly all else seems to be working so far, which is great!! : NMEA0183, NMEA2K, AIS, Venus plugin (input from a Cerbo GX).  

 Any thoughts advice appreciated.   Will hold (and be patient) if its known to be RPI5 related and part of changes due