I'm not sure if it's the gltf exporter or a Godot issue, but when importing animated meshes via GLTF2 exporter non manifold/open meshes do not seem to have the proper vertex weighting...
Can anone clarify whether it's just not supported, if it might be the exporter or I should just buckle down and do a whole bunch of tests :) ??? I just assume it's quicker if someone knows than me having to do a bunch of testing. :)