Picard Not Saving Multiple Entries

I have been using Picard for years but have always had problems when it comes to Picard saving tags with multiple values (e.g. Composers, Producers etc) Whenever I tag something it only ever saves the first entry of a field with multiple values unless I manually edit the tag to all be on one line which is time-consuming, especially with a large collection.

So am I missing something? I have Picard set to ID3v2.3 and use ; to separate multiple values

What file format is this? Do the multiple values show up when you load the files again into Picard? Which other program does not show these values?

If you want to flatten multi-value fields into a single one you can use a script like: