You can try going to Settings > General > Reset then tap "Reset Keyboard Dictionary". I think this wipes everything iOS has stored about your typing habits so it should hopefully fix the issue
I must have entered my wife's name in lower case at some point, because it autocompletes everyone else's names with a capital but leaves hers lower cased.
Ephil012|2 years ago
jamiepenney|2 years ago
sixstringtheory|2 years ago
beaugunderson|2 years ago