Under Miliband, it was a lot closer. They leaned Tory, but it was far from unanimous.
Under Corbyn, expect them to vote like US African-Americans. We've been here before. We know an existential threat when we see it.
The thing is; they quite clearly didn't. You look at the places that have reasonably large Jewish populations (mostly in London) and although they are distinct from London in terms of the swing to Labour being quite a bit less than the London average; there was still a swing to Labour. If there was some monolithic shift away from Labour amongst the Jewish community: the size of the community in those few seats should have caused a swing to the Tories but that did not happen.
e: Probably the big example is Hendon: 17% Jewish; Labour/Tory marginal seat (since it was recreated in 1997, its been a bellwether). In 2017; there was a 2.7% swing from the Conservatives to Labour in the seat; which can't possibly have happened if the Jewish vote was as monolithically Conservative in 2017. I assume that it probably swung towards the Tories; but less than the poll below suggests (from what I recall; it was taken a couple of weeks before polling day, when the overall polls swung quite strongly towards Labour). The same thing happened in Finchley and Golders Green as well: 21.1% Jewish: bellwether since 1997: 4% swing from the Tories to Labour. Both seats were below the London average or even what you see in other seats around (Chipping Barnet had a 6.9% swing to Labour and the Tories only just held it; that seat has never been won by Labour) and the Jewish vote most likely saved both for the Tories - but it isn't as monolithic as you suggest.
