When the listing gets posted the compatibility information is missing, while everything else is there, like variations and pictures.

This is driving me crazy because a few months ago this exact code was working just fine!

Also, I am posting to eBay motors US site and category ID 33702 (Seat Covers)

Here is my compatibility code:

         // Prepare eBay compatibility list data type.
         item.ItemCompatibilityList = new ItemCompatibilityListType();
         var compatibilityCol = new ItemCompatibilityTypeCollection();

         var compatibility = new ItemCompatibilityType();
         var NameValueList = new NameValueListTypeCollection();

         var yearPair = new NameValueListType();
         yearPair.Name = "Year";
         yearPair.Value = new StringCollection(new string[] { "2015" });

         var makePair = new NameValueListType();
         makePair.Name = "Make";
         makePair.Value = new StringCollection(new string[] { "Ford" });

         var modelPair = new NameValueListType();
         modelPair.Name = "Model";
         modelPair.Value = new StringCollection(new string[] { "Focus" });

         NameValueList.Add(yearPair);
         NameValueList.Add(makePair);
         NameValueList.Add(modelPair);

         compatibility.NameValueList = NameValueList;
         compatibilityCol.Add(compatibility);

         item.ItemCompatibilityList.Compatibility = compatibilityCol;