Just FYI - it's all fixed on my install. I'm running latest updates of everything (WordPress, Meta Box & MB Group).
@Jorgenlaaker - have you tried updating MB Group?
Having looked into this more it seems it's a problem with the main plugin.
Between 4.9 and now. (I've just reloaded 4.9 onto my system and it's working again!)
I'll post in the support section for the main plugin. https://github.com/rilwis/meta-box/issues/981
