Hi Tedward,
There was a similar issue in past that appears on the PCs with Wide Quad Extended Graphics Array Plus screens (referenced as WQXGA+ , QHD or QHD+ display) with resolution 3200x1800 pixels, such as Lenovo IdeaPad Yoga 2 PRO or Dell XPS 15
Below is a Bug report for the same.
https://support.symantec.com/en_US/article.TECH224009.html
Could you please confirm the SED version (10.3.2 MP9 is the latest version which is recommended) and the hardware details of the machine you are facing issue.