Someone must have adjusted the (found in Preferences: tweaks) Tweak.
Code:
#: Author sort name algorithm
# ID: author_sort_copy_method
# The algorithm used to copy author to author_sort
# Possible values are:
# invert: use "fn ln" -> "ln, fn"
# copy : copy author to author_sort without modification
# comma : use 'copy' if there is a ',' in the name, otherwise use 'invert'
# nocomma : "fn ln" -> "ln fn" (without the comma)
# When this tweak is changed, the author_sort values stored with each author
# must be recomputed by right-clicking on an author in the left-hand tags pane,
# selecting 'manage authors', and pressing 'Recalculate all author sort values'.
# The author name suffixes are words that are ignored when they occur at the
# end of an author name. The case of the suffix is ignored and trailing
# periods are automatically handled. The same is true for prefixes.
# The author name copy words are a set of words which if they occur in an
# author name cause the automatically generated author sort string to be
# identical to the author name. This means that the sort for a string like Acme
# Inc. will be Acme Inc. instead of Inc., Acme
author_sort_copy_method = 'invert'
author_name_suffixes = ('Jr', 'Sr', 'Inc', 'Ph.D', 'Phd', 'MD', 'M.D', 'I', 'II', 'III', 'IV', 'Junior', 'Senior')
author_name_prefixes = ('Mr', 'Mrs', 'Ms', 'Dr', 'Prof')
author_name_copywords = ('Corporation', 'Company', 'Co.', 'Agency', 'Council', 'Committee', 'Inc.', 'Institute', 'Society', 'Club', 'Team')
If you make changes, follow the instructions included in the tweak above.