Here is an update. As far as I know, the post office clerks told me that swap package was delivered to the correct address on December 24th. I told them my partner did not received said package and they refused to process an insurance claim. So I am out $40 for the swap box and shipping.
The only things I can think of: it was stolen, it is in the apartment complex office, or it is at a post office in the city it was supposed to be delivered.
I am sending out a replacement to my partner this week. I will get insurance and tracking (I only got useless insurance last time). It better get there to my partner this time. This is ridiculous.
Also, I'd like to thank the mods for understanding that I'm not flaking and that the post office can be disappointing in their lack of services.