we x posted - but FWIW
I would have gone into Manage Authors and
typed, over the top of what's there, the value I wanted in that author-sort column, i.e "
Mandel, Emily St. John". I have an idea that will set a flag in the database indicating author-sort has been defined by the user. That should prevent it being changed by software that implements fixed rules. That's what I had to do with
Garcia Xxxxxx authors.
Also check
Preferences->Tweaks->Author sort algorithm->Author name prefixes. Maybe 'St' has crept into that list, I recall someone having similar problems with abbreviated saints. Inevitably, they swore on a stack on books that they didn't put it there
BR