If I have understood Sergey Kuzmich’s post correctly, I have the same problem as he has experienced. I cannot switch to French from Spanish. I tried Italian from Spanish - this works. From Italian to French, however, I land back a Spanish.
I can switch from Spanish to French, but there is an error, it still says Spanish although the colors are right (blue and red) and the library and my imported content are french.
Now from French to Spanish it gets hooked up in French. But that’s just what it says at the header when I switch from one language from another, in reality it switched with its colours and all.
I signed out in the meanwhile and on my return the first page was French (which I got stuck on before), but now I cannot switch to Spanish - although the header changes to the Spanish colours. I’ll sign out again in a minute to check whether the first page will be Spanish…
No, checking out didn’t work this time. I’m stuck in French, with the headers changing to the respecitve language colours - nothing else is happening.
Dear friends. Greetings from Kiev. I transferred all of your messages to Google. If someone is well-understood structure of the site, please contact the system administrator of this site. (the text I wrote with the help of Google. machine has so far smarter than me)
Sorry about that. We were trying to speed things up by caching parts of the page. Back to the drawing board! 
It should be working fine now.
Yes it works now!
Thank you mark 