Simple Dipole Balun Issue

I'm building a simple half-wave dipole in HFSS. I first made a model with a lumped port in the center to find a good length/radius. I then
attempted to implement a full design using an "infinite" balun - I.E. I run the coax through one element of the dipole and attach the outer
conductor to one end and the inner conductor to another.

The issue is that I'm getting totally different impedance from what I would expect. Simple analysis (as well as my lumped port model) give a
real impedance of around 75 ohms at the resonant frequency. My dipole utilizing an infinite balun is giving me half that.

I checked with a bazooka balun and got the same result.

My patterns look correct, and I plotted the Complex Surface Current Magnitude on both elements and they matched very well. I have no idea what's
going on.

I've attached two images detailing the model - it's super straight forward, which further highlights my confusion.

Thanks for any help/advice!