If anyone could help figure out what is going on that would be great
Looks like you have calculated quarter wavelength at 4.7 GHz. You need to double the length of microstrip for 2.4 GHz. Check out the simulation and schematic. (I have use the same substrate and values you used)
Try to do EM simulation in ADS with the layout for better and accurate results.
Your microstrip lines are shown as 0.348" long, which is 8.84 mm. Given the speed of light in FR4 is roughly c/2 1, this corresponds to an electrical length of about 16 mm. As a Wilkinson is built with λ/4 line, it's tuned to a wavelength of about 64 mm, or a frequency of c/λ = 300e6 / 64e-3 = roughly 4.7 GHz, which is what your plot shows.
Double the length of the lines.
1 Very approximate, depends on geometry and frequency, especially with a horrible substrate like FR4, but it's good enough for gross back-of-envelope calculations like this.