simply run the series:false search, the select All (ctrl-A)
Use the bulk mode Metadata Editor to set that name in Series (and set index to 0 ) Series MUST have an index
But doing your way makes the DB larger as there are now MORE entries in the Series Table (this is internal)
My plan (stated with small disks and RAM)
Not setting a value IMPLIES a condition. Not Read, No Series, (no formats) Placeholder, wish list