PBF4 Can't use or edit page 4

When I try to cycle pages to page 4 (and sometimes page 3 also) I get forced back to page 1.

It was working fine. I did try to map “page_load(page_next())” to one of the buttons on each page previously - perhaps that has upset it?

Have tried clearing all settings and re installing firmware via Grid Editor but this does not solve the problem.

Hm, it probably has to do with each button triggering the Page change twice: once when pressed and once when released!
I would advise using a Press/Release block when moving Page changes to a button.

You can read more about this behavior here: Buttons triggering twice.