With the edit engine, all yaml is replaced with the order of database columns, then your fields that you don't use with the database are written. This way you don't lose any previous info.
About your metadata field I saw that if you have an empty field, when is "replaced" the way I explain, inserts a "null"
I will use this issue as a bug to fix that "null" set
Also I use the term "Metadata:" in all my notes and it looks like db-folder is adding something to that?
heres the edited file: