I have tried on different servers, the bug is always this.
If I choose a menu item of TZ Portfolio as the HOME of the site, as an error page I display all the Articles of TZ Portfolio +
You can try on https://tzportfolio.cloudaccess.host
where Main Menu> Home> TZ Portfolio Plus >> Single Article
The bug is linked to SEO, in fact it disappears if in Joomla> Global Configuration> Site> Search Engine Friendly URLs > NO