Hi, 
I had similar issue when using the system with prism/tilts. When I choose “use real rays” in the lateral color setting, this discontinuity goes away. I assume its coming from the paraxial ray or vignetting factors. If anyone has any idea on this root cause?

This issue could come from a number of different reasons:

• Vignetting Factors (only calculated once @ primary wavelength)
• Ray Aiming (only calculated once @ primary wavelength)
• Chief ray being clipped by hard-aperture

Even the Airy Disk has discontinuities around mid-field; the Airy Disk is a function of the effective f-number, which in turn is a function of RI (a ray's direction cosine in image space).  The RI calculation typically shows issues because of vignetting factors, so if you have vignetting factors, I would start there.  

If you can post your file, the community can help more.

We really need to file to be able to diagnose, but it’s easy to replicate the lateral color plot with a macro. I would try tracing some rays around the discontinuity to see what’s going on. For anything more helpful than that, we’d need to see the file.