I'm not having any problems on any device, but admittedly, I have a pretty high speed internet, up and down. Also, I always use Chrome on 'puter, but app for phone and ipad. Everything seems to be OK for me.
Well that specific watch has a **chronograph** and that is explicitly listed as a prohibited watch by LSAC. https://www.lsac.org/jd/lsat/day-of-test (keyword chronograph, youll find it)