Background downloads/updates

It might be background download. You said update, I assume it was a title update(patch) for a game. I think it didn't finish because updates don't work in background download mode.

another method is to not have other things running on the internet line while your updating if to many things are happening it will slow the process. Also another issue can be a update error if no other things resolve your issues

You could try and canel it and try reinstalling it

Instant is on and all the other options are on

Hello BaffleBum,

Thank you for your post. I understand you are experiencing an issue with your console failing to complete updates in the background. To ensure that your console will download updates while powered off, please ensure your console's power mode is set to "Instant
On". To verify this setting, please check out this page:
Xbox One - Power Modes.

I hope this helps!