You are right. It's a past continuous passive, and it means that someone was doing something at that time. Who that person was is not important - the important thing is that action was happening If you can supply the full context, we can explain in more detail.

There might be a problem at some point then a minute later it disappears. Let's say there is a bug in the program then someone reports that bug. Five minutes later, that person tries to reproduce the bug but he can't do that. He might say 'something HAS been done (by someone to fix the problem.'