2-word tags, separated by commas, are changing format once saved

I have converted my hardback book to an e-book.

One of the main problems I am experiencing is that 2-word tags eg Robert Pattinson, Wentworth Woodhouse, Intelligence Corps, once saved, are reverting to single words eg Robert, Pattinson,Wentworth, Woodhouse, Intelligence, Corps.

What is going wrong during the saving process?

Please can you help?

Thanks.

Monica Weller.