I also have the freezing issue. Have not enabled the new tuner mode. Just a simple layout with short/long press for scenes and presets up/down. My feeling is that when the FM3 freezes this happens after a long press of a footswitch. I clearly see this because the FW display shows the "inverted" text (2nd function for long press) when freezed. I could also see that suddenly the main display became almost white (the texts could still be seen in a very light grey), then the corners of the display became black, so there was a kind of white circle on the display. This one became smaller and smaller and in the end the display was completely black. Looked like a cool animation... The footswitch displays and LEDs were still on, although freezed.
Hope this is not too confusing and helps in finding the bug.