Possibly daft suggestion given it sounds like you know what you're doing, but is there only one element in your model of oven?
The oven in one of our rentals has thrown a trip and won't heat up, removed the heater element, thinking it was this, but it physically looks ok, ( normally they show signs of blowing ).
I've measured the continuity and that's fine, I've measured the resistance and, with the meter set on 200ohm I'm getting 44.1, the element is 1200w 230v.
By my working out that's about right, can someone correct me if I'm wrong.
Possibly daft suggestion given it sounds like you know what you're doing, but is there only one element in your model of oven?
OP, have you measured the element to earth, on both terminals? tripping would be a sign of earth leakage.
It may be that it only shorts when it expands when hot. Check it with an insulation tester like a 500v megger, that will show up any breakdown.
I had this on an oven and disconnected the parts to narrow down the fault and it was the fan in the end
I hope the element is ok as I can't get a new one, they have stopped making them
Assuming the breaker it tripped was an RCD or ELCB then, after the conductivity tests you have carried out, it is most likely the element is breaking down when it is hot.
Assuming the cooker works ok (everything switched on and up to temperature) without the suspect element fitted then refit said element and heat that only. It if trips then bingo that’s your problem.
I went through similar many years ago and discussed with an electrician. I was told was overthinking the problem and should go back to basics.
According to Ohms Law, 1200w at 240v is 5 amps. Power is V squared over R, so should be 48 ohms. Your reading is well within tolerance for the item and the accuracy of most multimeters. A resistive element will also change resistance when hot. More likely it's breaking down to earth so the megger test is crucial. Have you run the oven with the element taken out? Does it still trip?
Any other issues? Did your tenant have the oven cleaned recently as water could have got in somewhere.
For parts, if you need them, have you tried www.espares.co.uk or https://shop.ukwhitegoods.co.uk/cooker-oven-parts
The oven only tripped once, hence why the tenant called me.
I tripped it back in when I got there and switched the oven on, didn’t trip out again, but oven didn’t get hot enough, although the element did warm up slightly, hence why I think it might be the thermostat.