So, it works if you put a normal non-frozen item into the 3rd slot? (because it isn't saved by the IM).
That means, there are two options atm: Either fixing the HTD with this method or fixing the 3rd slot so that you can also freeze your 3rd weapon. But this will cause the full equipment being faked by the IM and therefore you will get a HTD, if I understood it right.
Very funny, you don't get HTD if at least one item is really in your slot