I had accounts on neither site, so perhaps that’s related. I tried to replicate on try, but chose to create an account rather than try to log in without one, and that worked just fine.
It’s an iPad mini, which I think few people use. I think that it sometimes gets treated as a desktop and sometimes a mobile, since it’s between those sizes.
When I returned to stonehearth on desktop, it properly redirected to get me to create the account.
Do you know what your user agent is? If it’s iOS it should match /iPad|iPhone|iPod/ and get the full screen login. I’m not sure what chrome uses but maybe it thinks you’re a desktop.