I totally agree here. For whatever trick of the mind cp14 has associated her two to full with her broken arm last year. We're not exactly sure when she broke it, or how, we realized two weeks later (this weekend actually a year ago) that she was tumbling on it broken and during that time she'd been working on no two to full so I guess that's where it comes from. But until she's ready to face that demon and throw it herself, she'll stay a where she is. And that's fine. The comforting thing is that when she is ready and she does decide to own it, she's got it. I think even she believes that, she's just terrified of that particular pass for some reason.
But you're completely right about age. Younger kids just seem to chuck stuff even when they crash and the desire to make coaches and mom happy they will go right back to it. Not so much with teenagers. Something about puberty (at least with girls) it's like they start realizing "this could be tragic" and the mental blocks come. I've seen kids with level 5 skills never able to go backwards ever again (literally) or lose two levels of tumbling all over blocks when they were fearless as pre-teens.