Contact groups, problem

Good afternoon. If the current group does not have an interface, it is taken from the parent group. Those. you need to remove the interface for the parent group, after which you will not have it applied to the current one.

I understand what you are talking about, but for some reason it does not work as you say.
I also have the task of removing unnecessary interfaces so that it stretches from one group.
In that that and a problem that the interface is not deleted.
80% were deleted normally, the rest are not deleted, and each such group has its own interface.
For example, there is such a branch of groups:
Ukraine WHOLESALE > Regions > Kiev delivery > Route Tuesday
1. Ukraine OPT - has its own new interface, from where it should stretch to other subgroups.
2. Regions - does not have its own interface, pulls it from Ukraine OPT, everything is ok.
3. Kiev delivery - the parent group costs "Regions", but has its own interface (old), which I cannot delete.
4. Route Tuesday - parent group "Kyiv Delivery" and also an old interface that I can't delete :(
Tell me, please, what to do? Something is clearly not right.)

probably because in point 2 there is already some kind of interface. That is, you could accidentally save. Delete it, save it. Then try to remove from point 3

Here is a screen, there is no interface in the "Regions" group, I deleted it, and after I deleted it, it says that "the interface is taken from the parent group Ukraine OPT"

And the subsequent groups behave like in the video, you delete the interface - it is restored.

Well, I tried to delete the interface several times from all these groups and in different sequences - the result is the same :(
I even tried to add something new, then delete everything and still the interface returns to the one that was originally.

Good afternoon Is there a solution to this problem?
This is some kind of obvious bug on the side of boxing, can I somehow fix it?
Everything would be fine, but we made a new contact card and now we are filling it out, but because of this bug it is impossible to work :(