Just after posting we found the issue. But I am curious about what you are saying about the history. For us the history is one big HTML and you cannot really see what the changes were. So hard to find out who or what they did.

 Try to look at the history of the process configuration source. You can access the old state, see the differences and even copy an old state over.

 See https://jazz.net//library/article/503 for how to use the process history.

We only use the webbased version of RTC. I guess that is why we cannot see the changes either than in the complete HTML.