Hello,
I am trying to model this OAP from thorlabs in zemax: Thorlabs - MPD269-G01 Ø2" 90° Off-Axis Parabolic Mirror, Prot. Aluminum, RFL = 6".
I am able to open in sequential mode, but when I want to convert it to non-sequential mode I get this (see below)

This happens when I do design lockdown or not.
I also want to swap the light source and imaging plane so the source is a diverging point source at the focal point and the light is a collimated beam off the OAP.
Any and all help is appreciated, thanks!