The issue here is both of the "word-order kind" and "of the particle kind". *問題は私が作りました [が, objective, BUT subject of the action] = (the problem/question-objective) (I-subjective) + verb: made. 1-Just as reminder: the ga particle indicates a subject among other possible subjects. Thus, in this case, it means "I, among the others" 2- 問題は is put in the first place as grammatical subject, this means that it is not a "general problem/question" but something definite which is already displayed or put under attention. The translation will be: "I was the one who made THE problem." or "That very problem was made by me" *私は問題を作りました [は subjective] is a straight sentence S+O+V, which puts emphasis on the action and not on the detail. The listeners are not aware of what kind of problem came up, just that I "made" one. The translation is simply: "I made a problem/question (nuance: and that´s what happened)" =NOTES= With 問題 you might also use 提起する (as "to raise a question/problem").

問題は私が作りました”と”私は問題を作りましたの違いは、主語がどこにあるかです。 The difference between those two sentences are what the subject is. -主語が”問題”の場合 問題は私が作りました -> The problem was made by me.　 -主語が”私”の場合 　 私は問題を作りました -> I made the problem.

”問題は私が作りました”は、”私”を強調しています。 問題は私が作りました　＝　私が問題を作りました