User-token is invalidated on every login from other device, so when I return to the previous one, I must login again. If I want to use my site on computer and a mobile device, I have to enter login-password every time. The same situation: when I run my site on the test server, I have to relogin on production after that. Another example: testing the site with different browsers.
It’s really unexpected behaviour. I have a user-token, my session haven’t expired, I haven’t logged out, why I must login again?
I think, you must allow to have simultaneous valid user-tokens for one user.