Conditions under which this bug occurs: - `SerializerNullValueHandling` or `SerializerDefaultValueHandling` is set to `Ignore` in `IJsonApiOptions.SerializerSettings` - The resource model consists of multiple attributes - A non-last attribute is set to `null` or its default value In this case, any attributes following the attribute whose value is `null` or default are omitted from the response body. This is caused by lines: https://github.com/json-api-dotnet/JsonApiDotNetCore/blob/d555bb5819daef746e7c5dfe77b1fe052161ed83/src/JsonApiDotNetCore/Serialization/Building/ResourceObjectBuilder.cs#L174 and: https://github.com/json-api-dotnet/JsonApiDotNetCore/blob/d555bb5819daef746e7c5dfe77b1fe052161ed83/src/JsonApiDotNetCore/Serialization/Building/ResourceObjectBuilder.cs#L180, which should `continue` instead of `return`.