Epanet app vs. epanet lib behaviour

Hello,
I’m using the epanet app to compare simulation results with the epanet.lib in python. I’ve noticed that there’s some drift between the two sets of results and, on closer inspection, these occur after a ‘System unbalanced’ report when running the epanet.lib. I take it that the app and the lib handle this situation differently, is that correct?

Best,
Gareth.