Batch mode does exist for SELECTED entries.
It called
Bulk Mode Metadata Edit and there is a tick box to SWAP Author Title.
Simply select all the entries (books) you want to do that operation on: Tap 'E' for Metadata edit. It will be in bulk mode,
As to Why? 2 possible causes: 1) you are NOT using the Adding Books option: read from metadata instead of file name. 1b )The template is in the wrong order... but you said
some so that is not a 100% fixable. 2)The book has dodgy metadata.




Quality check Plugin. It can help find all sorts of metadata issues (and FIX a couple the Bulk MDE can't do).