[Bug] Problem with multi select box

Hi, i`ve encountered a problem with multi select boxes: the values dont get saved. also when i look on the customers page there is Label: Array

See Screenshots:

http://gyazo.com/8797db458f08410cc2f04c6ea6df0eb9
http://gyazo.com/7a71d4dcadb70abce3e7c3769cdbb434

Any help would be highly appreciated!

Regards
joschi

https://ww.wp.xz.cn/plugins/woocommerce-poor-guys-swiss-knife/