GHS LCSS Plugin not working

Good afternoon,

I am having a problem dealing with the above mentioned AddOn. Since the latest updates I cannot use this AddOn any more (properly). 

Whenever I try t look for a structure it states, that my browser is not supported. Copy and paste, however, works to some extent.

However, I am using Firefox and Edge which are very common browers.

Anyone knowing a workaround for that?