I have been working for a few months on a book about the Orcas Island Chamber Music Festival 2018 season. One of the performers last year has the surname, "Thorsteinsdóttir," with that accent over the "o." That's the way I typed it into the book module, and that's the way I saved it, but each time I've reopened the book to make changes the festival people wanted, I've noticed several instances where "Thorsteinsdóttir" became just "Thorsteinsdottir." And the same thing seems to be happening at the other end: the festival people reviewing my manuscript keep catching "Thorsteinsdottir"s I was sure I had written as "Thorsteinsdóttir." It makes me look bad. This last go-round, thinking maybe I was just a bad proofreader, I inventoried every "Thorsteinsdóttir" in the book, making sure each one was correct. I asked the festival people to check all the "Thorsteinsdóttir"s, and they found all were correct. But when I reopened the book to make their other recent changes, four out of the seventeen "Thorsteinsdóttir"s I had inventoried had reverted to "Thorsteinsdottir." The file at all times has resided on my computer; no one but me has access to it (the festival people see a Blurb preview, not my file).
What's going on here? How can I stop it? (I don't think Ms. Thorsteindóttir is amenable to changing the spelling of her name.)