Well that wasn’t a solution. Turns out I need r.SkinCache.CompileShaders=True, or it causes other problems.
I’m guessing the problem concerns skeletal/skinned meshes.
On the old computer the project loads, compiles and the resulting game plays.
If I update the engine from 4.24 to 4.25, on the old computer, It casuses artifacts on the suspect skeletal mesh.
If I move the 4.24 project files to my new computer, which is also running 4.24, The same thing happens to the skelmesh - artifacting.
I will post some images in a while.