Update: I discovered that the board I have has different IDs. I've updated the rules to reflect that, but still no joy. Added rules: # Added 20230604 to match MH-ET Live ATTiny88 # Vendor ID: 1A86 # Product ID: 7523 SUBSYSTEMS=="usb", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", MODE:="0666" KERNEL=="ttyACM*", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", MODE:="0666", ENV{ID_MM_DEVICE_IGNO RE}="1"