some rocket scientist at MS changed how EMF "shapes" are processed. EMF is a meta data format of a shape (can parse or ungroup an EMF shape, but things like discrete geometries are not present).
Circa March 2022, MS had a visio build that introduced a bug into the EMF. The fix is to disable EMF optimizations.
(personally, I fixed this by growing the file cache in the OS from 4GB to 12GB),