Measurement protocol not registering item category

Question

We're sending item and transaction hits to Google Analytics using the "Measurement Protocol" API, using Ecommerce (not Enhanced Ecommerce). The requests are delivered successfully and Analytics web interface displays them, but it doesn't show all fields. For example, Item Name (in parameter) is there, but Item Category (iv) is not.

In Measurement Protocol documentation there are sample requests and links for testing them in "Measurement Protocol Hit Builder" (this seems to be the official tool). We used this Hit Builder to send similar requests to Google Analytics, but the category doesn't show up in them too. Here are the sample links for reproducing this (ti parameter should be changed):

• https://ga-dev-tools.appspot.com/hit-builder/?v=1&t=transaction&tid=UA-***&cid=555&ti=12345&ta=westernWear&tr=7&ts=0&tt=0&cu=USD
• https://ga-dev-tools.appspot.com/hit-builder/?v=1&t=item&tid=UA-***&cid=555&ti=12345&in=sofa&ip=7&iq=2&ic=u3eqds43&iv=furniture&cu=USD

These requests send the data to GA property. Item Category field is not getting registered neither via this tool nor via the PHP library that we use on the website.