When the page stays white after logging in to MyAgrovision, the URL used to reach the webpage is too long. It is not equal to my.agrovision.com. Then something old tries to load, and that does not work.
The problem is solved when the page is refreshed.
To solve it for now and always, the URL needs to be changed. Make sure the URL where the shortcut/bookmark refers to is only: my.agrovision.com and it will not happen again.