I have used a few ash saplings. Good wood
What I had was really elastic in tension and moderately elastic in compression. This is why, and not having a wide experience in bow making, I tended to underbuild a little the ash bows that I made (except for the last one - lesson learned maybe).
Also, compared to other woods I used, the ash I used seemed quite light (in terms of physical weight) for the stiffness.
From the 5 ash selfbows I made, 4 took set visibly and 2 developed a few thinny frets. All 4 were a little underbuilt in my opinion.
One (the last I made) took no visible set (and no frets, of course).
The only ash backed bow I made, 34 lb only, had no set and no chrysals (despite having draw length to ntn length ratio a little over 1/2; bendy handle).
No ash bow broke.