Hi albertov ,
Thank you very much for your post.
I've tried to reproduce the issue on my side but it's working fine for me. It may be a conflict with a 3rd part plugin. Are you able to deactivate all the plugins except ATUM, Multi-Inventory, and WooCommerce and see if the problem is still there?
Note that deactivate plugins could cause some issues. I recommend you to do that in a staging site.