I just tried a test. I opened three files, one after another using Ctrl-O. I named them “Test File 1”, “Test File 2”, and Test File 3". I pasted the same contents into each file.
Then, I created three files using Ctrl-Z (my shortcut for the Zettelkasten plugin). Named them “Test Zettel 1”, “Test Zettel 2”, and “Test Zettel 3”.
Right after doing this, I went back to each note and found that several of the new files were completely empty.
Test File 1 and Test File 2 had the full content. Test File 3 was now empty.
Test Zettel 1 and 2 were both empty, and Test Zettel 3 had the full content.
In my Dropbox version control, I can see that the file was truncated right after I ran the Ctrl-Z command.