Often problems with web based applications can be fixed by opening the web browser in a special mode which will start the application with no remembered sessions. Depending on the browser this will be named differently (Incognito, InPrivate, Private Browsing, etc.). When your browser enters this mode it will act as if the user has never used this browser before. Sessions made in the normal mode are not removed and will return once the user uses a non-private browser window.
To start a new Private browser window:
In Chrome:
Hotkey: Ctrl+Shift+N (⌘+Shift+N on a Mac)
Or, click the three vertical dots in the top right corner of the browser and select "New Incognito Window".
In Edge:
Hotkey: Ctrl+Shift+N
Or, click the three horizontal dots in the top right corner of the browser and select "New InPrivate Window".
In Firefox:
Hotkey: Ctrl+Shift+P (⌘+Shift+P on a Mac)
Or, click the three horizontal lines in the top right corner of the browser and select "New Private Window".
In Safari
Hotkey: ⌘+Shift+N
Or, in the menu bar select File > New Private Window