You refuse to see me as my age.
It's quite odd, and yes, no fun.
Until I was five, you'd just disregard me,
And then you just saw me as one!
When six, you vividly saw me as two,
Following that, thinking me four.
But then at nine, you did announce
That I was inextant once more.
Hint (Added Oct 19, 2024):
The enigmatic tag was included from the beginning to show that this is not a typical riddle. According to the PSE definition, a riddle "gives indirect clues about an unnamed object or concept to be identified, often in a poem format". This enigmatic puzzle could be argued to also be a riddle because the word "indirect" is used. It could also be argued that it is an enigmatic puzzle masquerading as a riddle.
Hint (Added Nov 13, 2024):
This "riddle" gives direct clues to [something], which you must then figure out how to use to get the word. Once you find the word, look for a clue to verify it.
Hint (Added Nov 20, 2024):
One of the tricky things about this "riddle" is that the lines are not giving indirect clues about the answer word, like a normal riddle does. Instead, they are giving direct clues to a [something], and then you apply that [something] in a certain way to find the word. Therefore, the answer word is not clued by, or even hinted at by, the meaning of the title or text.