I'm not using a metadata plugboard at the moment, but I know other people are and they are working. I did just test a simple set the title to a text string and it worked fine here.
The only thing I can think of is that you are sending a book to the Touch that is already on it. If so, the file will get updated, but the Touch will not reprocess it to read the metadata. To do this, you will need to delete the book from the device and then send it again. My Kobo Utilities plugin can update the metadata separately, but it doesn't use the metadata plugboards when doing this.
|