Uuuhh Mangal. That hurts. I had also a situation where I lost money (only 100€) when restarted Z5 on a newer version. That was because the meaning of a slider had changed.
Yesterday I changed from 1.24 to 1.26 of Zorro at my Z5 instance. I still have old trades from June but no new trades since market open. So there is really something wrong with your Zorro instance.
When I change to a new version before I start trading again I do a test so that I now history is there and the slider have some setting. After that I set the sliders as I had them on the old version and start trading again.

You are sure that the slider setting are the same as on the old account?
How did you do your update?