I can't export the animation of the .abc file after having added a texture atlas ??

Hello there,
i have an alembic scene (.abc) file from a butterfly with a wing animation. I haven’t made it myself.

I imported it into blender to be able to create a Texture Atlas.

When i create a Texture Atlas for it. I lose the possibility to export the .abc file with the animation.

If i select all the objects, to prepare to export them as an .abc file, then it becomes green,…see picture:


So to clarify my problem:

If i just import the .abc file into Blender --> and then don’t do anything to it --> and export it straight out again as an .abc file --> then i keep the animation.

Only when i create teh Texture atlas for it --> i lose the possibility to export the file with the animation

I hope somebody can help?
greetz lenny