I have never seen a version of Studio where it ISN’T a problem to be honest. I currently have 18.104.22.168, and I had the more recent edition for a while until it started having issues with Carrara. Just try an experiment with your own version of Genesis on your own computer for me. If I’m right, it should not matter what computer or version of Studio you have. Take the model down to about .5 in the basic child morph. Now pose his hand. Notice that the fist doesn’t really close. Now fiddle with the dials to make it close. Notice how the joints start thinning for some reason?
Take a screen shot if you would, I want to see if this issue is as universal as I think it is.