After looking through your project I have found that you appear to have circular dependencies in your Character blueprint. This could be what is causing the errors that you are seeing. The dependencies that I have found appear to be those between your Character and your soldiers. After reading your post about how things work one time through after deleting your saved files, this theory becomes even more likely. I hope that this information helps.
I deleted all circular dependencies between the character and the soldiers (MyCharacter has references now to the soldiers, but not the other way round) and checked for correctness using the reference viewer.
But that wasn’t it. Blueprint events still work in editor and still fail when packaged.
I revisited your project and I was able to to the UMG to function.I did this by snagging the current widgets that are being displayed on screen and placing them as children into a new master widget. I hope that this workaround may prove useful for your project.