I don’t see this as a shutter speed issue as other posters mention. Every lens stopped down to f2.x or more will have very shallow depth of field. So some part of the photo is likely sharp but not the eyes which is the target for portraits. Especially with a subject that won’t hold still try stopping down to at least 5.6 and set your light for the same.
You should also review how to use high speed shutter with flash. Does your camera support HSS? If so, 1\160th isn’t in high speed zone… that would be anything over the the fastest default shutter your camera is designed to use, usually around 250th or lower. The band means that you have settings in conflict which results in the shutter over the sensor for part of the flash duration. Easily fixed.
https://strobist.blogspot.com/2014/09/education-gear-for-your-brain.html