Hi
I'm getting this, too - in VS 2017, with the .SCSS file downloaded from Theme Studio.
Error in plugin "sass"
Message:
wwwroot\css\ejsbootstrap.scss
Error: Base-level rules cannot contain the parent-selector-referencing character '&'.
on line 10898 of wwwroot/css/ejsbootstrap.scss, in mixin `@content`
from line 111 of wwwroot/css/ejsbootstrap.scss, in mixin `export-module`
from line 10679 of wwwroot/css/ejsbootstrap.scss
>> &.e-bigger .e-switch-wrapper,
----^
Hopefully that's enough to track this issue down.
Kind regards
Richard