After I upgraded to 4.8 I noticed that the group layers do not work anymore. They do not draw and can no longer be turned on/off individually. The layers are grouped in the REST service, and previous to 4.8 they always worked ok. I just went back to 4.7 for now, but wanted to report this issue, as I would like to be able to use the newer versions in the future.
I attached screen shots of the layerlist for the 4.7 and 4.8.