OS: MacOS 10.14.6

I am cutting surfaces to make flat patches in freeview (Freesurfer 7.1.0) on and flatten them. The flat patches appear to have distortions (https://imgur.com/a/KwG3iTa). This process worked well in FS6.

I use

mris_flatten -w 10 <input_file.3d> <output_file.flat> to flatten them.

Additionally, when I use mri_surf2vol to convert the patch to a 3D nifti volume, I get an error.

mri_surf2vol --ribbon <mri/ribbon.mgz> --o /<roi_patch/oc_full_patch.nii.gz> --subject <sub> --so </lh.inflated> </lh.occipital.patch.flat>

ERROR: MRISreadCurvAsMRI: <path/to/freesurfer/recon_all/surf/lh.occipital.patch.flat, vals/vertex -12428437 unsupported

Any idea why this is happening?

Thank you,

Dev