Sometimes a website will show a blank page when you expect it to show the login page. This is normally caused by corrupted cookies and site data stored on your computer. To fix this you need to clear the cookies/local data stored about the site. 

To do this first click on the settings icon the Chrome omni bar (address bar) as shown below and pick  the site settings option (yellow arrow).

 On the next screen click the "Delete data" button

Then on the next screen click the "Delete" button

One you have done this close this tab and also close the original site tab you had issues with. Then try going back to the site and you should be presented with the login screen as normal.