Microsoft has acknowledged a small error on the Xbox One that causes games to display that they are installing past 100%. Currently it seems to impact games that have title updates awaiting them, including Halo 5 and Grand Theft Auto.
According to an Xbox staff member, Microsoft is working on a fix:
"We have determined that the user experience of over 100% install is impacting all titles that are digital and have a pending/current title update. We are getting preview reports of both Halo 5 and Grand Theft Auto showing this over 100% install issue, you will see other titles as well reporting this error."
"The game will install correctly just let it finish and a fix is being worked on."
It should be noted that this issue doesn't appear to cause any actual problems with the games themselves.