@Loewchen, aforementioned friend here,

here are the saves in question, also a list of mods we use:

Savefile that can be loaded, but breaks any new save done by it:
https://www.dropbox.com/s/oux9ruxblm6sy8v/ffs3.zip?dl=0

Broken savefile:
https://www.dropbox.com/s/m0c8bn0593hhgba/ffs4.zip?dl=0 ...