Device control exclusion doesn't work

We have Bitdenfender Endpoint security here at my work. Due to the nature of our business we do not allow usb flash drives to be plugged in to any computers, with some exceptions. I have added a flash drive exclusion from discovered devices, and I can see that the device is in the list, but every time I plug in the flash drive it gets blocked. The only way to allow a flash drive is to log in to Power User and allow external devices in Device Control Rules, but then that allows all flash drives and we can't have it that way. Is there something else I need to do?