What hypothesis suggests Venus's core prevents a dynamo from operating?

Answer

The core may have cooled too slowly, solidified, or exists in a stagnant state.

A primary hypothesis suggests that because Venus lacks plate tectonics to shed heat, its core cooling rate may have led to solidification or a stagnant state that halts the necessary convective motion for a dynamo.

What hypothesis suggests Venus's core prevents a dynamo from operating?
EarthVenüsplanetsmagnetic field