That’s most probably because her TMDB page doesn’t have an IMDB link, so her credits are not imported or even deleted from Trakt, causing a loss of relevant data.
We already asked a couple of weeks ago to remove this IMDB link requirement, at least for people, but of course no answer or explanation from anybody. 
See here: https://forums.trakt.tv/t/remove-imdb-and-tvdb-requirement-for-tmdb/107030/4