But the module is missing on the published site.
Page title contains apostrophe.
This problem has been fixed in Parallels Web Presence Builder since version 11.5.4:
2. What's New
[+] new feature
[*] functionality improvement
[-] bug resolved
Parallels Presence Builder 11.5.4
21. [-] Users were unable to see the Commenting module on pages containing an apostrophe in the title.
- Upgrade your edition of Parallels Web Presence Builder to version 11.5.4 or above
- avoid using apostrophe in page title.