you are using a TEST RELEASE which has bugs.
Do not make things more complicated then they are.
Until it is fixed in HB simply install a WoW Addon that repeairs for you everytime the bot talks to a vendor like: https://mods.curse.com/addons/wow/autorepair
Easy and smart workaround
Regards
BotOp
PS: Next time please use the support section and add a logfile. In case of a test release use the test release thread to report bugs.