Lead Developer
Hi there,
If you’re using WordPress 4.1+, GeneratePress is using the built in title-tag which comes with WordPress. This means GeneratePress leaves the title up to WordPress, or plugins that manipulate it (SEO plugins). https://make.wordpress.org/core/2014/10/29/title-tags-in-4-1/
Do you have an SEO plugin installed? Maybe do a quick search on this specific issue with Polylang and that plugin?
I haven’t used Polylang much, but I’m thinking this issue may be caused by the plugin itself, or your SEO plugin.
Maybe try contacting the plugin author to see if they can offer any advice – if it’s something GeneratePress related I’ll definitely take a look 🙂
One thing to test: Try switching the theme to TwentyFifteen for a moment – if the title displays correctly, we know it’s GeneratePress related and I can debug further.
Let me know 🙂