I answered you via email. Posting here in case anyone needs it:
I see you’re using the old syntax of Meta Box to register meta boxes. I’ve made the change to this: https://ghostbin.com/paste/d2k7b
Please try it.
Note that the way to register directly via class
RW_Meta_Box is not supported anymore. While it might work in normal cases, it’s not compatible with other extensions. Please see the docs here: https://docs.metabox.io/creating-meta-boxes/
Let me know if you see any bug.