Stubborn - The facts are the facts, and ISTJs tend to resist any new idea that isn't supported by them. This factual decision-making process also makes it difficult for people with the ISTJ personality type to accept that they were wrong about something – but anyone can miss a detail, even them.
Insensitive - While not intentionally harsh, ISTJs often hurt more sensitive types' feelings by the simple mantra that honesty is the best policy. ISTJ personalities may take emotions into consideration, but really only so far as to determine the most effective way to say what needs to be said.
Always by the Book - ISTJs believe that things work best with clearly defined rules, but this makes them reluctant to bend those rules or try new things, even when the downside is minimal. Truly unstructured environments leave ISTJs all but paralyzed.
Judgmental - Opinions are opinions and facts are facts, and ISTJs are unlikely to respect people who disagree with those facts, or especially those who remain willfully ignorant of them.
Often Unreasonably Blame Themselves - All this can combine to make ISTJs believe they are the only ones who can see projects through reliably. As they load themselves with extra work and responsibilities, turning away good intentions and helpful ideas, ISTJs sooner or later hit a tipping point where they simply can't deliver. Since they've heaped the responsibility on themselves, ISTJs then believe the responsibility for failure is theirs alone to bear.