Password protection not functioning

Spoke too soon in previous post: Password protection isn’t functioning either.
As soon as a password is entered into file downloads manager, the url link shown when hovering over the download button is the wp install location. This is fine in itself as file url/access code isn’t revealed.
However, when the correct password is entered, the user is still redirected to the WP install url, i.e. the WP site home page.
Please advise.

following up for support on this issue

Hi Shaon, I found that nextgen gallery plugin was preventing this from functioning. After I disabled NG, the password functionality has started working again. Re: the stock count issue in another post, disabling NG has not resolved this.