Since Simulation engine reuses the runtime engine it replaces (overrides) NodeInstanceFactoryRegistry entires to not use regular implementations for Nodes and provide its own implementation that collect simulation results instead of actually executing the process instance.
Currently it simply overrides the static instance of NodeInstanceFactoryRegistry causing the runtime engine to always use simulation nodes instead of regular after single simulation execution.

Simulation should not override the regular entries but instead provide its specific implementation of NodeInstanceFactoryRegistry via ksession's environment and then runtime engine should get access to NodeInstanceFactoryRegistry instance via method (getInstance(Environment) and not the public static field