Hi, we are not able to scan HTTPS connections in IE (and EDGE) without our own certificates being injected into the browser.
This behavior is expected in IE even on the latest version on Avast.
The certificate is created adhoc and signed by Avast Web/Mail shield root. All attributes of the certificate are kept the same (such as Common Name or validity periods), just the issuer must be your very own PC, in order for the local scanner to be able to decrypt the traffic and scan it.
Please see the FAQ for more detailed info:
https://www.avast.com/faq.php?article=AVKB190#artTitleYou can turn of HTTPS scanning in the WebShields settings dialog if you don't like it.