After casting Spellbound Heart V I will get the skill and running buff but right after I cast my Summon: Keeper Gorr it will cancel my running buff.
Hi, since the June 14th patch note, the spellbound heart buff is already included in the buff you get from summoning Tett/Gorr:
https://www.naeu.playblackdesert.com/en-US/News/Detail?groupContentNo=5387&countryType=en-US