Extension freezes when using two displays

I'm using a Surface pro 4 on Window 10 Version 1709 build 16299.371 . Chrome is Version 66.0.3359.139 (Official Build) (64-bit)

I've noticed that when using an external monitor on my surface with the display mode set to extended, if i have chrome open on my dell monitor, the resizer app is basically unusable. If i click the extension in the top right corner, i cannot click on anything further. It's just frozen. 

If i set my display to the dell monitor only, it works fine. 

I'm not sure if it's a bug or if it's like this by design but it's a bit of a deal breaker.