Dear Rich,
Please open "\CuteSoft_Client\CuteEditor\Configuration\Security\Default.config"
Change
<security name="filenamePattern">^[a-zA-Z0-9\._\s-\#]+$</security>
to
<security name="filenamePattern">^[a-zA-Z0-9\._\s-\#\u0026]+$</security>
Thank you for asking