Hi again,
In both Firefox and Opera there is a dialogue window where you can choose which languages the websites should be displayed in. You arrange them with the language with the highest priority at the top and the lowest at the bottom. I tested this by putting German at the top and keeping Swedish and English in the list (but with lower priority). Logically, with our changes in Polylang, this should make the website show the English version (since there is no German version), but it still shows the Swedish version.
However, when I remove all languages except German, the English site is being served as intended. So, for those not having Swedish in the list at all, everything should work as intended. It is still confusing though that the prioritization didn't work - I don't think it's a browser bug since the same error appears in both Firefox and Opera.
Best regards,
Johan