[universalgrl]

If the fuses on the AA shell were PTTF ( powder train time fuses) which were adjustable for the mount of time till detonation these I believe were later replaced by proximity fuses.
If the powder train which was in a serpentine grove machined into two sections of the fuse body was interrupted there would not be a detonation at the preset altitude and the shell would continue on a ballistic arc till the shell returned to impact the ground where it may or may not explode.
Fuse types are super quick or impact, impact delay, PTTF, proximity or others that I don't know about.
I have a background in military explosives and years as a commercial pyrotechnician.