Yeah, this is a pretty serious bug, and I think there have been other reports of it floating around, where people mysteriously lose data without any apparent cause. It’s good you were able to find a reproduceable scenario for it.
I’ve always suspected that Katalon generates scripts using reflection, and that’s why, for each script you write, Katalon generates a “.tc” file as well as a “Script0123456789.groovy” file. Not sure if that’s actually what’s happening behind the scenes, just a guess, but I wouldn’t be surprised if the bug lives within this process.