Hey Fillip H., I just tried again with my host to set that value and to change the setting one more time, but it still doesn't save.
I mean... I can sincerely stay with it, it's not a big problem (even in terms of SEO) for me, but maybe you shuuld recheck that it's not a code issue in the plugin itself. It's strange as only that field doesn't save and the others are working well.