Please double-check that your hyperlink doesn't contain spaces or illegal characters. As an example, Word does not support the pound character (#) in a hyperlink.
I also have a workaround that Jay Freedman originally mentioned: Create the hyperlink, then right-click on it and choose
Toggle Field Codes. The truncated hyperlink will display. Go back to your browser and in the address bar, select the portion of the address that was cut off. Copy it.
Back in Word, click at the end of the hyperlink but before the double quotes. Paste in the remainder of the link. Right-click and choose Toggle Field Codes again to revert to the normal hyperlink display.
Finally, in Word, click on the smiley face in the upper right corner of the Word window, choose
Tell Us What Can Be Better and file a bug report.