I have created a form, which works fine on my Desktop on multiple browsers. I share the link via email. When trying to open the link the form won't open. Brings me to the Forms page but it just sits there spinning. If I go to forms.office.com and login, when prompted, and then go to the link it brings me to the form and it loads just fine from my phone.
It appears as if, on an iPhone, haven't tested others, that when opening a shared link it isn't redirecting the user to login first.
This is all being done through my companies Office 365 account. When I do have to login, and I am redirected appropriately to do so, it brings me to my companies sign in page or allows me to choose my company login that is cached.