Hey guys, so to start things off, this girl and I are close and whenever I tease her about anything she always seems as though she's being attacked?

Which is odd because she always seems to brush off my compliments or try to downplay them (apparently she does this to everyone from what my friends have said when they've tried complimenting her about something) and yet whenever I make the slightest joke she calls me 'salty' and whatnot.

An example: she regularly takes a selfie pulling a certain move (finger on her face). I imitate and send a selfie back with a caption teasing her (something along the lines of "guess who") and she then goes on to post the same pic on instagram with a caption saying something like "<my name> keeps making fun of me" and that leads to her friends complimenting her and reassuring her while also making me seem like a dick. (Also she seems to react a lot to her close girl friends complimenting but not guy friends? Odd) I should clarify, she posts it on a second private account with just friends so it's not as a message or anything

I'm not sure what to do in a situation where she calls me 'salty' or 'mean' when I'm trying to playfully tease her? She's very insecure about herself, maybe that's the case? I mean she has a sense of humor and I try to make it painfully obvious that I'm joking when I tease her but to no avail.

Any ideas?