I can confirm this behaviour, which seems to be of recent origin. A hyperlink copied from another mail message or from a Word document is not active when pasted into a new mail message.
Here is an example, where the content of a received mail message (a notification from Microsoft Community) has been pasted into a new mail message. The top part shows the snippet as received, the bottom part shows it after pasting. It has been converted to
Quoted-Printable ready for transmission; this means that equals signs ('=') within the markup are changed to '=3D' and line-ends are marked with equals signs.
Note that the hyperlink reference (href) attribute of the anchor (a) tag has been moved within a style= attribute, rendering it useless:

Exactly the same happens with hyperlinks copied from a Word document.
I'll speculate that this conversion (HTML to CSS) is carried out by one or other of the Internet Explorer libraries. These were all updated by the installation of Internet Explorer 11, in your case on 14 November. If this is right, a lot of people will have
to complain to persuade the IE product team to restore the previous behaviour. Perhaps the mods could find out for us.
You could see whether the problem goes away if you uninstall IE11 using the function under
View installed updates under Programs and features in Control Panel.
Meanwhile, it's worth mentioning that hyperlinks in signatures seem not to be affected. Perhaps this would be a better and simpler way of inserting standard content into mail messages.