I do not know, it works fine here (Chrome 54, Windows 7). Perhaps some extension you have installed causes this, try to disable extensions one by one.
If it still does not help, does it reproduce in other browsers?
If it does, it is a YouTube issue and you should use the "Send feedback" link at the bottom of YouTube.
If it does not, y
ou can search
crbug.com for an existing issue and star it. If you cannot find one, file a new issue using the "New issue" link on the same page.
Please, do not add a "+1" or "Me too" or "Confirmed" (or similar) comment. It just wastes the time of Chrome engineers and sends unnecessary e-mails to all of the people who starred the issue.
You can reply with a link to the found or created issue and might get triaged (and fixed) faster.