Crashing - LG UltraFine 5K, FCP 10.3.4 and High Sierra

well I have found a massive bug with LG monitor...

15 inch MBP 2016

High Sierra

10.3.4 FCP

Never had this problem with 10.3 FCP and Sierra....

Computer functions normally until I try and use FCP...

Open FCP with Laptop open, 2xLG connected = FCP loads and functions normally

Open FCP with 2xLG connected = FCP immediate crash

Open FCP with Left LG connected = FCP immediate crash

Open FCP with Laptop open, Right LG connected = FCP loads and functions normally

Open FCP with Laptop open, Left LG connected = FCP loads and functions normally

Problem is with the laptop open I can not use the two LG for FCP

So right now if - Open FCP with Laptop open, 2xLG connected then do the import etc then I can close the Laptop then it works fine.

If I - Open FCP with Laptop open, 2xLG connected then close the Laptop and do the import then it crashes...

These are monitors with nothing attached... tried it with and without my usual stuff on the monitor hubs and no real difference....

has anyone else found this??? anyone any ideas???