Thanks.
I searched this property and found some relevant case.
billboardMode on a gltf assets doesn’t works as it should - Bugs - Babylon.js
I am kind facing the same issue. When this property enabled, it basically disabled the billboard mode…
Currently I am doing some manual mapping from a parented “normal” plane to a “billboard” mode plane. I still keep the same hirachicy as its logically should look like. Thus I did not use the trick suggest in the link above (create dummy parent).
Set a Pivot | Babylon.js Playground
Which seems working alright…
Not sure if the situation will get better with your fix. Will try it out later.