Hello,
cannon seems to behave differently between BJS version 4.1 and 5.0
I have a physics controlled mesh (icosphere). This mesh has two child-meshes attached (blue boxes).
See this PG: Babylon.js Playground
With version 5.0 the blue box meshes seem to “sink” into the ground whereas with version 4.1 it behaves more as I would expect. I don’t think it’s related, but maybe it has something to do with a problem I’ve described here: Cannon physics undetermined behavior with HeightmapImpostor
Thanks for any help 
There was an issue that was solved (i believe in 4.2) with compound meshes and cannon.js (and other engines as well, actually). It seems like this fix has a certain effect on meshes connected to a parent that has rotation prior to setting the physics impostors.
Try setting the rotation after creating the impostors and it will work as expected - physics version differences | Babylon.js Playground
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