Right, so windows currently returns grid serial numbers as “Mxxxxxx” with the upper-case “M”. pymonome detects varibright grids by the lowercase “m” followed by numbers, so that’s there the problem comes from.

For now, you can directly modify pymonome source locally to fix the serial number matching regexp, completely disable varibright detection or set grid.varibright to True in your script.

The long-term fix for this would be to mangle serial number a bit in serialosc, so the number is the same across all platforms.