Lightning - Logging in as another user.  I sometimes end up in this big loop of this error message (see attached), when trying to login as another user in lightning or when I log out of user I'm logged in as want to go back to logging in as me.  It seems sometimes I don't get this, then other times I have to click the Log In button 4-5 times for it to work. I also have at least once or twice a day where I couldn't get it to go to log me in as another user.  I had to use a different browser or sometimes just try again later.  We are using chrome most of the time.  Sometimes if I switch to firefox I can get it to work, but I still see the error.  

I've tried on both browsers and on both I seem to have to click several times to get the login as another user to work.  

I'm logging in as other users quite frequently as we are getting ready to go live with some functionality and this how I'm testing changes as we make them. 

Is this a known issue somewhere or something that is just happening to us for some reason.  I can open a case if no one else has seen this before.