A 4 byte UTF-8 character incorrectly failing maxlenght facet.

A 4 byte UTF-8 character incorrectly failing maxlenght facet.
The data is F0 9D 90 80 and is a 4-byte UTF-8 sequence to represent 1 character.
It is failing with
Error at file input.xml, line 4, char 17
Message: value '??' has length '2' which exceeds maxLength facet value '1'
when running sax2count.exe

This looks like a limitation but I could not find any documentation about it in the bug list.

*Input XML*

<?xml version="1.1" encoding="UTF-8"?>
<Root xmlns="http://www.example.org/Test" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.example.org/Test
Input.xsd">
<Data>𝐀</Data>
</Root>

*Schema*

<?xml version="1.0" encoding="UTF-8"?>
<schema targetNamespace="http://www.example.org/Test" elementFormDefault="qualified" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://www.example.org/Test">
<element name="Root">
<complexType>
<sequence>
<element name="Data">
<simpleType>
<restriction base="string">
<maxLength value="1"/>
</restriction>
</simpleType>
</element>
</sequence>
</complexType>
</element>
</schema>