Place chicken breasts in the bowl of the instant pot.
In a small bowl or glass measuring cup, whisk together the hot sauce, melted butter, Worcestershire sauce, and red wine vinegar.
Pour buffalo sauce over the frozen chicken.
Close lid and set to sealing.
Cook on high pressure for 25 minutes.
Natural pressure release.
Remove chicken from instant pot and shred.
Set the instant pot to saute. Whisk in the cornstarch.
Add the chicken back into the sauce and let simmer for 5 minutes, until thickened.