I had a similar problem once.
First thing that came into my mind was:
the temper is ruined. Becuase yours is antique and maybe it has been recently purchased by you,
you donīt know what it has been through. Maybe someone ruined it.

But in my case it was a brand new Wacker that I had for 6 months without problems.
I even sharpened it several times without any problems.
But once I got exactly those semilunar chips everytime I finished.

I couldnīt get rid of that, no matter what I did.
So I decided to send it to a honemeister,
who had no problems at all.

It must have been something I did but did not see.
So maybe you try to just give it someone else
and see if he encounteres the same problems.

If you want to try something, try to finish the blade on the norton 4k side
with chromium oxide afterwards. Maybe you will bypass the problem this way