Hi Konaswimmer-
Yes, you’re going to have issues with SU 2015 on Sierra. SketchUp itself may run ok, but LayOut will have a number of issues as detailed in the first post of this thread. You’ll also experience the issues listed in the “SketchUp and El Capitan” thread.
If you want to have a version of SketchUp that officially supports Sierra, you’ll need to use the latest maintenance release of 2016 or the newly released 2017.
thanks,
Marc