Here is the case of use. I create a dataset that inherits the volume (root: wheel) and I put from the interface the following ACL: bop group in total access and I save. When I go back to the ACL page I do not have any information about the owner or the previously positioned group bop. On the other hand if I do a getfacl everything is OK.
The problem is that in this case if I add an ACL it removes all those previously positioned.
The case is reproducible each time. I did several tests on different machines.