AIUI (and IIRC correctly from a previous discussion on another board) the Allies were VERY paranoid about VT shellsDeploying proximity fuses means running a risk of them being captured. That was one big allied fear that stoped their deployment in the ETO.
to the point that initially they were only deployed where there was little chance they might be found and copied
In the ETO an early large scale use of AA VT was vs the V1
but it took an appeal by Eisenhower to release the stocks for use during the crisis stage of the Bulge
- not as AA but for Antipersonnel barrages
(Supposedly, Patton loved VT ... saying something like "this is going to change the face of land war" )