Turns out SmartThings wanted us to remove some of the features and integrate our driver into their zigbee-switch driver. So this thread is kind of obsolete. Well, most of the code was taken from this wwst driver and integrated into the the pull request for their zigbee-driver switch. So testing the driver above did help since it is a lot of the same code. Since the driver is a lot smaller, it is easier to test. This is our beta channel and the driver is called Zigbee Switch if anyone is interested (but we have already submitted the PR).
https://bestow-regional.api.smartthings.com/invite/kVM5XrQYDxj5