Layer properties window not showing

I have also had this problem but I discovered a solution. I found that if I had Storyline open on one of my two monitors the Slide Layer Properties window would not display normally. The solution, I discovered, was to drag Storyline from the monitor screen down onto the laptop screen and then click on the cog to bring up the Slide Layer Properties window. It then displays normally! Then you can drag Storyline back up to a monitor screen and you're back in business. Very bizarre!