In the LinusTechTips review he mentioned only top 5% dies go into Threadripper. So if it's related to quality of Ryzen, then that might make sense. I'd be surprised if Threadripper isn't plagued by this bug, though.
TR uses the same Zeppelin dies as Ryzen. Just the top 5% binned parts.
Epyc uses a newer die stepping that isn't yet used for Ryzen or TR.