Error reference page modal when trying to link to a page in OctoberCMS

Hi there,

I am very new on here and new also using the fantastic OctoberCMS. I am implementing a website that for some reason lost a native capability: reference a static page in the CMS UI.

I am trying to link to a page that was created in the CMS, I am selecting the Page Entry and then the reference, it shows perfect, but the option CMS Page under it does not load anything, which is required.

Can someone point out where should I look at to solve this problem?

For reference, see the print-screen.

Thank you for helping me out.

Kindly,