Yeah the fact that it doesn’t work via iComms is a good indication there’s something going on with the panel. On my panel arming has always worked with iComms and via this Home Assistant integration, but the thing is, we enabled the iComms integration many years before I developed the integration, so I didn’t have precise knowledge of what needed to be changed/enabled on the panel.
Wild thought - perhaps it might be worth contacting Ness support about this, given that it doesn’t work from their app directly?
Sounds like the new boards might be using a newer protocol with some changes in it, so would need to obtain the newest copy of the protocol documentation (which I’m having trouble finding, and sadly the link to the original doc is now broken)