Language display is this a bug ive found or have i got it wrong ! ?

Hello all
I have set up a v3.9 store. Ive input sample data in a number of languages as i wish my store to be multilingual.
But for now i want the store to only use and display Spanish.
My store is tonerangel.es
i have set the default language to be spanish.
But If i turn off all the other languages and leave only spanish the content pages do not display in spanish but in the standard option (which is english)
If i turn ON any of the other languages ie. Spanish and English then spanish language works again !
is this a bug?
is there  a way around this?
Thanks !
David

also the store also does not seem to actually be able to switch between english and spanish.
this bug seems to occur when you turn a language off then back on. Even clearing caceh/restarting doesnt fix it..

anyone else have this issue?