Leonardo,
Here is the warning message:
[Warning] ST-Sim: At least one Transition Target has been defined with a non-primary Transition Group.
I am running version 2.0.44 of SyncroSim and version 3.1.44 of stsim.
I do have one transition simulation group defined but it is not one that I am using for transition targets.
I have been unable to find where one sets primary vs non primary groups. I found another thread where someone was asking the same question. It seems that the documentation link has been moved somewhere else. The answer is probably super obvious but I am just not seeing it.