So, @georgegalloway was right, the faked anti-semitism campaign targeting Corbyn was put on hold in August. ProQuest finds national newspaper articles mentioning 'Corbyn' and 'anti-semitism':

July 2019 = 1,086

August 2019 = 167

August 2018 = 1,700

Who paused it and why?

— Media Lens (@medialens) September 4, 2019