This seems to happen most frequently when initially starting a fight and re-positioning the combat dialog box but I've also had it happen when grouping toons. Happened most recently at 9:15 PM MST. It's frequent enough that it's inhibiting gameplay, I see others have also experienced the issue with no resolution. Any help would be greatly appreciated.
Running as admin in compatibility mode for XP SP2
i7-7700K CPU @ 4.20GHz, 4 core
NVIDIA GTX 1080 Ti