The fact that my way of presenting arguements in subjective discussions as a means to put some feelers out to test my own framework of the idea often ridiculed for not being important enough to consider, resulting in discussions that could only be construed as hostile, only to find out neither side was being hostile.
INTJ's have a rigid and bland way of communicating through text that is hard to read for NTP's, who are always trying to puzzle as much together between the lines as possible. An INTJ is good in masking how they reached their conclusions and what they feel about those conclusions while presenting them.
Whilest INTP usually construct their thoughts in similar ways to how they themselves reached that conclusion, mostly because they feel that their viewpoints will be better understood if they do.
INTJ's see opinions as straight lines that do not require you to deviate from, INTP's wish to deviate from those straight lines to look for information that may, or may not be, important to the conclusion that is to be reached.
Realizing this has made it much easier for me to connect and communicate with some of the smart and intellectual INTJ's on here.
IRL: Don't know any INTJ that I deal with closely, but there is an ENTJ.
Main source of frustration, ENTJ's will try to get everything, and I mean everything, out of their way as soon as possible, I've never seen the ENTJ I know postpone something without feeling bad about it. INTP's prefer to be laid back and do things in their own time. This causes much friction.