Update coming! Brave testers needed!

[Fatalist]

That's a weird one. Try changing it to:
<unit meter="1" name="meter"></unit>
remove its msh file and reload it in an editor.

As for the objects changing positions, that's a hard one for me to solve without seeing the files. It could be that the meshes are no longer properly attached to the bodies of the entities.

Size has changed, but position too.
And collider box size not = object size.

Spoiler below!