awesome plugin! Though after struggeling with ajax & polylang, I may have found an issue.
Two languages (de,en), default is de.
Pretty links are on.
The ajax request:
Polylang_Core::curlang after setup_theme() points to 'de', so pll_current_language() fails & the wrong lang id is injected to WPs SQL strings.
What seems to be a solution is to add yours & g100g's ajax check to the regex switch in Polylang_Core:setup_theme, line 233, so the second regex is triggered.