This location on your local hdd, is it a non-icloud folder? I’ve heard of icloud causing blank documents in Scriv projects.
Also, see this A year on and I am still trying to recover from a catastrophic loss of Scrivener work - #20 by kewms post by kewms and some of the other messages in that thread for more about this blank documents thing, backups, and related info. Also, for anyone who read this, if you haven’t read Alternative Method of Keeping Projects Synced / Cloud Syncing / Knowledge Base - Literature and Latte Support then it’s worth your time to read it (you might have already read it Marco, but other people who read this could find it useful).
Also yes scrivener’s built in backup ability is awesome! I have it set to make a zip on every project close with the date and to never delete old ones (I disable the only keep 10 or whatever), and it has saved me before.