creating a third site in a network language is missing

Hei,
I have a multi site with two languages, English and Russian. I have now opened two more, a German and a Spanish one. The German is ok, , but the drop down menu in the plugin doesnt show the Spanish language. It only shows, Russian, English, German and Chinese.
What do I have to do to get the Spanish language showing up as an alternativ in the drop down meny in the plugin?

Thanks in advance for your answer ??

https://www.ads-software.com/plugins/multisite-language-switcher/