portfolio items are not recognized of the same category

Hi,
let me explain:
use theme studiofolio http://demo.undsgn.com/studiofolio/
After I installed Polylang, including latest release,
navigation between items in the same category assigned within a portfolio is no longer possible, I believe that the association is not recognized to the same category of the portfolio .
Also, trying to change several items at once with bulk action ,
generates this error:
Warning : Illegal offset type in / htdocs / public / www / wp / wp- includes / cache.php on line 571 Warning : Illegal offset type in isset or empty in / htdocs / public / www / wp / wp- includes / cache. php on line 617 Warning : array_key_exists () : The first argument Should Be either a string or an integer in / htdocs / public / www / wp / wp- includes / cache.php on line 617 Warning : Illegal offset type in / htdocs / public / www / wp / wp- includes / cache.php on line 571 Warning : Illegal offset type in isset or empty in / htdocs / public / www / wp / wp- includes / cache.php on line 617 Warning : array_key_exists () : The first argument Should Be either a string or an integer in / htdocs / public / www / wp / wp- includes / cache.php on line 617 Warning : Illegal offset type in / htdocs / public / www / wp / wp-includes / cache.php on line 571 Warning : Illegal offset type in isset or empty in / htdocs / public / www / wp / wp- includes / cache.php on line 617 Warning : array_key_exists () : The first argument Should Be either a string or an integer in / htdocs / public / www / wp / wp- includes / cache.php on line 617 Warning : Illegal offset type in / htdocs / public / www / wp / wp- includes / cache.php on line 571 Warning : Can not modify header information - headers already sent by (output started at / htdocs / public / www / wp / wp- includes / cache.php : 571 ) in / htdocs / public / www / wp / wp- includes / pluggable.php on line 1121

Thanks in advance to anyone who can help me.

https://wordpress.org/plugins/polylang/