HI nathanschwarzbein ,
Thank you very much for your post.
I am sorry to hear you have issues saving some changes in Stock Central. We are not aware of any bugs and please, do update the latest release (from 8 hours ago) that included some fixes relating to this.
Regarding supplier change - it has never been possible as it is not coded yet. For further info, I recommend browsing the documentation in this forum.
Hope this helps.