While trying to steal both Runebooks and Spellbooks i get the msg (you cannot steal this item). so im not failing the theft. only not given permission. I could understand if the spellbook was a newb item. but runebooks are not newb items to my knowledge. ive also had the exact same issue with stealing mage regs.
As far as runebooks, they can not be stolen by clicks, only by a random steal. Spellbooks are newbied and cannot be stolen. With mage regs, I'm assuming you're trying to steal newbied regs from new players, and that's why they aren't being stolen. Pretty sure Jack of Shadows has had great success reg stealing
There was a bug that allowed runebooks to be stolen directly that was corrected with Patch 14. However they can still be stolen if they are in your base backpack by a random steal. Spellbooks are one of the few items on Renaissance that are blessed. Runebooks and Bulk Order Books can only be stolen with random steals but will drop on death. Stack stealing of items has been buggy and is scheduled for a fix in Patch 17. When stealing from a stack it calculated a random amount from the stack to steal regardless of how small a stack. (Incorrect Mechanic)