Hi there!
That does seem very strange. My only guess is that the board uses PWM signals from pins that are not PWM capable, but I don’t think so because why would the shield be designed for an Uno.
Try plugging the Uno in without the shield and see if a sketch can be uploaded to the board successfully. If that doesn’t work, then you know something could be fried on the board. If it does work. Then perhaps try to manually route connections from the arduino to the necessary pins on the board using wires instead of plugging the shield into the Uno and see if it works that way. Make sure that all power connections go to the correct location.