Hi there!
Many thanks for the detailed report! As you described, it seems to me that it is indeed a compatibility issue. Before I take a look into the sample project, I guess we can try the following:
Plugin order:
- EliMZ_Book
- Vs Core Engine
- EliMZ_MessageActions
- Vs Message Core
Either way, I think Message Core must be below all others so you can keep the choice size the way you want.
Other thing you can try is, see if the visustella message core has a way for you to change the Icon escape code to be another one than \i. Because maybe what is conflicting is this. Both plugins using \i to draw icons.
Let me know if any of this solves the issue.