I have just realised that the arrowhead scaling percentage no longer works as it should.

Scaling an arrowhead to 50% no longer means that the size is reduced to 50%, it the arrowhead only shrinks to something like 90%.

Similarliy, a 200% size adjustment gives me around 110% the original size. See image.

Not even a 1% setting gives me the 50% size I'm looking for.

I'm on a MBP M3 Max with InDesign 19.1.