The Shingles tool in LWCAD 2018.31 for LW (Windows 64bit 2019.5) doesn't appear to work like the videos show.
In the video, the shingles apply only to a roof object and they look correct. For me, unless I select the top roof polygons, shingles are applied to the ENTIRE object. They are also angled weird and have end caps placed wrong.

This looks like you have activated Shingle tool in perspective viewport.
Click in the viewport defines the ground of the object.

You have to click into top viewport.

I will give that a try, thanks.