Hi Mariusz,
Welcome to Qsm Pro Support Forum. Sorry for delayed response as it was weekend.
It seems like you are having either plugin or theme conflict. Next thing to do is to check for any plugin conflict or theme conflict. To do this, disable all of the plugins at once and enable them one by one by checking which one is causing the conflict. If this does not resolve the issue, change the website’s theme to another theme and check whether the issue is resolved or not.
If this doesn’t resolve the issue then you can use “WP Rollback” plugin to revert to the previous version of the plugin. It would be very helpful if you can copy the current setup of your website to a staging website so that we can look into the issue if troubleshooting steps mentioned above doesn’t work.
Please let me know regarding the same.
Regards,
Kriti