Alin,
Thanks for the detailed description of the bug. It helped me to reproduce it. I have recorded this issue as Case 18752 for consideration. I can't promise when this will be fixed but we will inform you when that happens.
Since JKI State Machine Editor is open source, you can post any issues in GitHub: https://github.com/JKISoftware/JKI-State-Machine-Editor/issues
Take care and stay safe.