How does one explain the irrational fear of approaching problems?
Fear of failure (Atychiphobia) is a form of specific phobia that may to some degree explains your situation.

However, please DO NOT instantly think/feel that you're experiencing a mental disorder or something similar. I cannot stress this enough, sharing some characteristics or experiencing some signs/symptoms of a disorder does not immediately means that you have that disorder.

I stated "to some degree" because features of "fear of failure" matched what you described, but only partly so. Note that in the linked explanation, on most cases, this fear will make a person avoid distinguishing him/herself and instead strive for mediocrity. However you have had achievements that clearly distinguishes yourself.

Instead, I would argue that you have such expectations of yourself, and the thought of failing to fulfill them are so great that you rather not try unless you're sure you will succeed. And when you did succeed, you tend to undermine/ brush-aside your own capabilities; since having such capabilities would mean that you're expected to achieve even more things in the future.

There are many articles discussing about this, and many offers ways/strategy to overcome this particular fear. For example this article. However I'm sorry that I couldn't find related books, papers, or scientific publications. All in all, I would personally advise you to stop thinking about results, and try to just "jump" the problem.

Hope this answer helps in any way!