I've always felt that it's something of a contradiction to be very or highly ambivalent. It's grammatically correct, as far as I know, but is it stylistically acceptable, or is my sense of linguistic style correct?
Cambridge defines the adverb form thusly:
...and highly ambivalent would mean the same, but to a greater extent. While correct, the phrase is fairly empty without something to compare it to. One could be ambivalent about [x] and highly ambivalent about [y].