Just some thoughts - I still have a lot to learn about cognitive functions so a lot of this might be inaccurate. Part of the reason why I'm posting it is so I can hear feedback, so feel free to point something out if it strikes you as wrong.
A lot of this relates to what [MENTION=10496]skylights[/MENTION] said previously.
A possible source of conflict between INxJs and IxFPs (especially INFPs): In their interactions with others, Ni+Je wants to fill in the blanks as much as possible, while Fi is very sensitive to being prejudged and takes it very personally. From what I've both read and seen in real life, INxJs naturally make these big intuitive leaps and tend to form pictures of something even from a small amount of input. As long as the INxJ is healthy, these pictures of reality are dynamic (and are sometimes nearly accurate from the beginning anyway); they change as more input comes in, so their prejudgments aren't really a big deal in the long run. Basically, they judge quickly but are aware of the lack of 100% accuracy in those judgments and are open to changing their opinions. Unhealthy INxJs are a different story, but I won't get into that here.
For IxFPs, however, judgments are usually a big deal and, except in cases in which someone crosses their personal values, are formed more slowly. They're very sensitive themselves to feeling like their voices are being lost in translation; being incorrectly judged feels like being erased/buried under other people's incorrect assumptions, and feels painfully depreciating, especially when they value the person judging them. Because of this personal sensitivity combined with their empathy, IxFPs are also extremely sensitive about seeing others being incorrectly/unfairly judged and will stand up for them if they believe it's happening. For an INFP who has enough NeTe to balance out FiSi, when getting to know someone they will juggle various possibilities about what that person could be like instead of forming a single
but also dynamic vision like a healthy INxJ. As the INFP learns more, Te narrows down the possibilities until they finally make a definite judgment about the person. Because Te is the INFP's inferior function, reforming those Te judgments is usually a pain in the ass so they tend to be pretty static, or at least not often changed. (Unless the INFP has very good use of Te.) (There are also more layers to this that I'm not going into detail about; usually there are little Ne doubts dancing around and trying to pick the Te steel locks.)
I guess my main theory is:
Because IxFPs are so sensitive to being judged, and also because 1) their own inner experience with using (inferior) Je suggests that it's very final and judgmental and 2) the flexibility of Ni in the healthy INxJ isn't always externally obvious, the judgments of the INxJ can come across as offensive, closed-minded and arrogant to those IxFPs who don't understand the INxJ's strategy of forming a single, dynamic vision (which has nuances that are difficult to articulate) instead of juggling multiple possibilities and waiting to form judgments like a Perceiver (esp. NP). This sensitivity can come across as prickliness or "boo hoo, poor me" egocentric hypersensitivity to INxJs. Similarly, INxJs can miss the depth in the IxFP's microcosmic way of thinking, understanding people, and forming values; also Ne in NFPs can make them appear shallow and wishy-washy to INxJs who don't understand the Fi core underneath Ne means we can juggle possibilities without actually changing our minds all the time.
Another general clash:
- To some Ne-users, Ni+Je can appear too inflexible (even though it's not if the individual is healthy). I believe that to some Ni-users, Ne (especially without Ti) can seem like mentally bouncing around the room at 100 mph.
- As previously touched on, INFPs tend to view the self as a microcosm through which others can be understood, and I think this approach can seem too limited to the INxJ and their more macroscopic approach.
- These are generalizations and, assuming they have validity, there are still going to be exceptions in every case.
- What I said about INFPs forming judgments slowly can be thrown out when someone crosses their deeply-held personal values. In that case, we can be VERY judgmental.