Shelly 1PM Mini Gen 4 - difficulty resetting to Matter

I have a 1PM Mini Gen4 that I used briefly in ZigBee mode (I wasn’t sure at the time that the power monitoring would still work via Matter, I now know it does) & it seems to be stuck that way.

A factory reset (holding the button for 10+ seconds) doesn’t seem to re-enable Matter. I want to use Matter as Homey Pro seems to be very poor with ZigBee (my Aqara switches were the same until I used an M3 hub to connect them via ZigBee & using the M3 as a Matter bridge).

Any suggestions on how to get Matter working again (if it is actually possible!)?