Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - General Certain skillbooks not on vendors. Ever.

There are some skillbooks which never appear on vendors.
I've personally ran into not finding:
Dust Devil
Whirlwind
Walk in Shadows

I've used the save/reload trick dozens of times and never have these appeared. A little internet search found a few forum posts on other boards with people having the same issue.

Is this intended or a bug?