Some update about cleanup issue. I had some turnaround, working with N5.5 and cleaning with N4. It works. Well I mean, that’s what I thought…
I had a cleanup on 2 whole years projects and backup then. I’ve been opening some of these projects yesterday and here’s what I got: on some projects, some files are missing, I even have one project folder with an empty Audio folder, not one single audio file, project is gone 
(
Let me say I’m used to cleanup feature, I’ve been using that for many years and I know about archiving before cleaning so that all files are located inside project folder, no faulty process here. But it looks like cleaning with N4 can cause errors and delete useful files.
Once again, I can’t understand why this feature doesn’t work anymore with N5.5… This is a main feature, not a daily one, but a fundamental one for a professional use of Nuendo.