On behest of Dmitry, I move my issue from GitHub here:
The Gantt-app works fine in my macOS Sierra environment with all my projects but one. With this one project, the program starts, the main screen opens, the planer report pops up and then the entire program freezes. Apple’s program manager defines the program as not reacting.
I can open any other project directly before or afterwards, but not as long as the program is frozen. If I lost the data it would be a hard hit.
I would not feel comfortable to share the file publicly. Is there any help I could get?