Altissimo struggle

Hey guys! This past year I’ve been working on improving my altissimo range (and learning triple octave scales)

I have absolutely no problem hitting altissimo c to altissimo f, and no problem hitting altissimo g, G#, and A (for triple octave A Major and G Major) but for the life of me I cannot get altissimo F# to come out consistently!

I do long tones on the altissimo chromatic scale, as well as on my third octave scales. I have no problem holding every note for over a measure, except F# always sounds for a second then cuts out!

My old clarinet teacher thought it was like a “second break” for me I just needed to overcome. My current clarinet teacher thinks it could be a gear issue (theory is the barrel, because I have better luck on other barrels that I’ve borrowed of theirs) but even with trying my teacher’s old mouthpieces and barrels I still have trouble getting the note to exist!

I was wondering if anyone else had a similar experience and what they did to get past it!