Since 5.0, when an Ellipse is linked to a generic Mesh, it seems to display at the wrong position as if it is increasingly “drifiting” from origin. It did not behave like this in 4.2.
I made a playground (#NUZWAZ) to show the difference between an Ellipse linked to a Mesh and an Ellipse linked to a Sphere.
Hey, turns out this was actually a regression in the way that we calculated bounding boxes. @Cedric has created a fix and it has already been merged, so you should see it in the latest version of Babylon available tomorrow 
fix physics regression by CedricGuillemet · Pull Request #12337 · BabylonJS/Babylon.js (github.com)